Fabrication of functional device mounting board making use of inkjet technique

ABSTRACT

An apparatus for fabricating a functional device mounting board comprises a holder for holding a substrate on which functional devices are to be formed, a jet head for ejecting a droplet containing a functional material onto the substrate, and a data input unit for supplying droplet ejection information to the jet head. The jet head ejects the droplets onto the substrate based on the droplet ejection information so as to form the functional device in the functional device forming area. The functional device is formed by allowing a volatile ingredient of the droplet, while allowing a solid component of the droplet to remain on the substrate.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to fabrication of afunctional device mounting board, using an ejector to form a functionaldevice on a substrate. More particularly, the present invention relatesto an apparatus and a system for fabricating the functional devicemounting board, as well as a functional device mounting board itselffabricated using the apparatus or the system.

[0003] 2. Description of the Related Art

[0004] In recent years, luminescent devices (or light-emitting devices)using organic materials have been developed for use in a spontaneousluminescent display, which has been spreading in place of a liquidcrystal display. In general, the luminescent device is formed using aphotolithography technique to pattern a layer of a functional materialinto a predetermined shape. For example, it is-known that an organicelectroluminescent (hereinafter, referred to as “organic EL”) device isfabricated by forming a layer of a low molecular-weight material byvapor deposition (or vacuum evaporation), and then patterning the layerby photolithography. See “Organic Electroluminescent Diodes”, C. W. Tangand S. A. VanSlyke, Appl. Phys. Lett. 51, 913 (1987). To fabricate acolor organic EL device, different luminescent materials are formed onprescribed pixels by vapor deposition. However, since vacuum evaporationand photolithography are high-cost processes requiring a number ofsteps, it is disadvantageous to employ these techniques to fabricateluminescent devices over a wide area.

[0005] To overcome this problem, the applicant has come across an ideathat inkjet droplet ejection means can be used to place a functionalmaterial at a desired position, without employing high-cost processes,such as vacuum evaporation and photolithography. Inkjet droplet ejectionmeans are disclosed in U.S. Pat. Nos. 3,060,429, 3,298,030, 3,596,275,3,416,153, 3,747,120, and 5,729,257. It is expected that a technique ofinkjet droplet ejection can be replaced for photolithography, and thatthe inkjet technique can realize more stable formation of a functionaldevice at low cost and a high yield rate.

[0006] For example, when fabricating an organic EL device as an exampleof the functional device, a pattern of a hole-transporting layer and alight-emissive layer can be formed on a transparent electrode substrateby ejecting a solution, in which a hole-transporting material and aluminescent material are dissolve or dispersed in a solvent, from theinkjet head.

[0007] The same idea is disclosed in JPA2000-323276 and JAP2001-60493.However, these publications only discuss the materials for organic ELdevices suitable to the inkjet method, and do not sufficiently refer toeither an apparatus for forming such a functional device on a substrateusing an inkjet technique, or a functional device mounting boardfabricated using the inkjet technique.

[0008] Applying the inkjet technique to fabrication of functionaldevices is not easy because the conventional inkjet technique is limitedto ejecting ink onto paper. There are still many unsolved factorsconcerning how to eject a solution containing a functional material ontoa substrate in a stable manner. Especially, a great deal of work isrequired to realize a group of functional devices formed on a substrateat highly precise patterns efficiently.

SUMMARY OF THE INVENTION

[0009] Therefore, it is an object of the present invention to provide anovel apparatus for fabricating a group of functional devices on asubstrate at low cost using a simple technique. This apparatus iscapable of fabricating the functional devices at high precision, andaccordingly, it can produce a high-quality functional device mountingboard.

[0010] It is another object of the invention to guarantee safe operationeven if a solution containing the functional material leaks out due toan unexpected accident.

[0011] It is still another object of the invention to preventundesirable clog in the jet head in order to guarantee reliable ejectingoperation.

[0012] It is yet another object of the invention to provide a system forfabricating a functional device mounting board.

[0013] It is yet another object of the invention to provide a functionaldevice mounting board with a precise pattern of functional device array.

[0014] It is yet another object of the invention to provide an imagedisplay apparatus using the functional device mounting board.

[0015] To achieve the objects, in one aspect of the invention, anapparatus for fabricating a functional device mounting board isprovided. The apparatus comprises (a) a holder for holding a substrateon which a functional device is to be formed, (b) a jet head forejecting a droplet containing a functional material onto the substrateso as to form the functional device in a functional device forming areaof the substrate by allowing the volatile ingredient of the droplet tovaporize, while allowing the solid component to remain on the substrate,and (c) a data input unit for supplying droplet ejection information tothe jet head. The jet head ejects the droplet onto the substrate basedon the droplet ejection information so as to form the functional devicein the functional device forming area.

[0016] With this apparatus, functional device mounting boards can befabricated at high precision using a simple structure.

[0017] The apparatus further has a driving unit that moves at least oneof the jet head and the holder relatively to the other so as to define adroplet ejecting area of the jet head broader than the functional deviceforming area of the substrate. tion.

[0018] Preferably, the jet head ejects the droplet using a mechanicaldisplacement force so that the droplet becomes spherical immediatelybefore the droplet reaches the substrate.

[0019] Alternatively, the jet head ejects the droplet using a mechanicaldisplacement force so that the droplet has an elongated shape along theejecting direction without a trailing droplet, and so that the length ofthe elongated droplet does not exceed three times the diameter of thedroplet.

[0020] These arrangements allow the apparatus to form a prescribedpattern of the functional, device at a desired position on the substrateprecisely.

[0021] The apparatus further comprises a reservoir positioned under thesubstrate for containing a solution of the functional material, and aflexible tube connecting the reservoir to the jet head.

[0022] This arrangement is advantageous as a safeguard preparing forunexpected leakage of the solution.

[0023] The apparatus further comprises maintenance equipment positionedoutside the holder. The maintenance equipment caps the droplet ejectingface of the jet head, and evacuates the solution containing thefunctional material from the jet head.

[0024] This arrangement effectively prevents the solution containing thefunctional material from blocking in the jet head.

[0025] The jet head may be comprised of a set of multi-nozzle jet headsarranged apart from each other. In this case, each of the multi-nozzlejet heads has a row of nozzles, and is capable of ejecting a droplet ofa different type of solution of the functional material. The jet head ismounted on a carriage driven by the driving unit, so that the row ofnozzles of each of the multi-nozzle jet heads is not parallel to acarriage moving direction.

[0026] For example, each of the multi-nozzle jet heads ejects adifferent type of solution containing an organic electroluminescentmaterial that emits light of a different color.

[0027] Preferably, droplet ejection speed is faster than the relativemoving speed between the jet head and the substrate.

[0028] In another aspect of the invention, a system for fabricatingfunctional device mounting boards is provided. The system comprises (a)a fabrication apparatus that fabricates a functional device mountingboard by ejecting a droplet of a solution containing a functionalmaterial from a jet head toward a substrate held on a holder, whilemoving the jet head relatively to the substrate, based on dropletejection information supplied to the jet head; and (b) a clean airsupply unit that supplies clean air to the droplet ejection area on thesubstrate.

[0029] In still another aspect of the invention, a functional devicemounting board, which is fabricated by the above-described apparatus orsystem, is provided. The functional device mounting board comprises (a)a substrate having a top face and a rear face, (b) a group of functionaldevices arranged in a matrix in a functional device forming area definedon the top face of the substrate, and (c) an information pattern formedoutside the functional device forming area on the top face of thesubstrate. Each of the functional devices is formed as a dot imageformed by one or more droplets of a solution containing a functionalmaterial.

[0030] The information pattern is also formed as a dot image, andincludes, for example, an identification pattern of the functionaldevice mounting board, or a performance check pattern.

[0031] Each of the functional devices is formed of a different type ofthe solution containing an organic electroluminescent material thatemits light of a different color.

[0032] In yet another aspect of the invention, a functional devicemounting board comprises (a) a substrate having a top face and a rearface, and (b) a group of functional device arranged in a matrix in afunctional device forming area defined on the top face. The roughness ofthe top face is at or below 0.5 s. Each of the functional devices isformed as a dot image formed by one or more droplets of a solutioncontaining a functional material.

[0033] Preferably, the roughness of the rear face, of the substrate isgreater than that of the top face.

[0034] A groove or a ridge may be formed on the rear face of thesubstrate.

[0035] These arrangements prevent the substrate from being stuck on thesubstrate holder of a fabrication apparatus.

[0036] At least one of the corners of the substrate are chamfered orrounded. Alternatively, the edges of the substrates are chamfered. Thisarrangement allows easy and safe handling of the substrate.

[0037] In yet another aspect of the invention, an image displayapparatus using the functional device mounting board is provided. Theimage display apparatus comprises (a) a functional device mounting boardhaving a group of functional devices arranged in a functional deviceforming area on a first face of a substrate, and (b) a cover platefacing the functional device mounting board. Each of the functionaldevices and the information pattern are formed as a dot image formed byone or more droplets of a solution containing a functional material.

[0038] Preferably, the thickness of the cover plate is greater than thatof the functional device mounting board.

[0039] The cover plate is made of, for example, reinforced glass.

[0040] In yet another aspect of the invention, an image displayapparatus comprises (a) a functional device mounting board having agroup of functional devices arranged in a functional device forming areaon the first face of the substrate, and (b) a holder having a curvedgroove. Each of the functional devices is formed as a dot imaged formedby one o more droplets of a solution containing a functional material.The holder holds the functional device mounting board in the curvedgroove so that the first face of the functional device mounting board isbent with respect to a viewer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other objects, features, and advantages of the present inventionwill become more apparent from the following detailed description whenread in conjunction with the accompanying drawings, in which:

[0042]FIG. 1 schematically illustrates, in a perspective view, ejectionof the solution containing a functional material onto an ITO transparentelectrode on the glass substrate;

[0043]FIG. 2 illustrates the overall structure of a fabricationapparatus for a functional device mounting board according to anembodiment of the invention;

[0044]FIG. 3, illustrates a droplet ejecting apparatus used to form afunctional device on a substrate according to an embodiment of theinvention;

[0045]FIG. 4A and FIG. 4B illustrate the jet head unit used in thedroplet ejecting apparatus shown in FIG. 3;

[0046]FIGS. 5A and 5B illustrate an example of the substrate on whichfunctional devices are formed, the substrate having a U-shaped groove onthe rear face of the substrate;

[0047]FIG. 6A and FIG. 6B illustrate another example of the substratehaving a V-shaped groove on the rear face of the substrate;

[0048]FIG. 7A and FIG. 7B illustrate still another example of thesubstrate having a ridge on the rear face of the substrate;

[0049]FIG. 8A illustrates an examples of the rectangular substratehaving chamfered corners, and

[0050]FIG. 8B illustrates another example of the rectangular substratehaving rounded corners;

[0051]FIG. 9 illustrates still another example of the rectangularsubstrate having a chamfered corner and three rounded corners;

[0052]FIG. 10 illustrates yet another example of the rectangularsubstrate having chamfered corners and an indentation on a side of therectangle;

[0053]FIG. 11A and FIG. 11B illustrate yet another example of therectangular substrate with chamfered edge lines;

[0054]FIG. 12 illustrates the corner of the substrate having thechamfered edge lines;

[0055]FIG. 13A and FIG. 13B illustrates yet other examples of thesubstrates having a chamfered corner formed on the chamfered edge lines;

[0056]FIG. 14 illustrates the positional relation between the jet headof the droplet ejecting apparatus and the substrate on which functionaldevices are to be formed;

[0057]FIG. 15 is a plan view of the substrate placed on the substrateholder;

[0058]FIG. 16 illustrates a shape of the droplet ejected from the jethead of the droplet ejecting apparatus according to the invention;

[0059]FIG. 17 illustrates another shape of the droplet ejected from thejet head of the droplet ejecting apparatus according to the invention;

[0060]FIG. 18 illustrates still another shape of the droplet ejectedfrom the jet head of the droplet ejecting apparatus by making use of thebubbles;

[0061]FIG. 19 illustrates an example of the functional device-having afunctional material formed by one droplet between the electrodes;

[0062]FIG. 20 illustrates another example of the functional devicehaving a functional material formed by several droplets between theelectrodes;

[0063]FIG. 21 illustrates still another example of the functional devicehaving a functional material formed in two lines between the electrodes,each line consisting of several droplets;

[0064]FIG. 22A through FIG. 22C illustrate examples of thermal-type jethead suitably applied to the droplet ejecting apparatus of the presentinvention;

[0065]FIG. 23 is a front view of a multi-nozzle type jet head;

[0066]FIG. 24 is a front view of a jet head unit in which severalmulti-nozzle jet heads are stacked, each multi-nozzle jet head beingused for a different type of solution;

[0067]FIG. 25 is a perspective view of the jet head unit shown in FIG.23;

[0068]FIG. 26 illustrates still another example of the multi-nozzle jethead unit having a common nozzle plate;

[0069]FIG. 27 illustrates yet another example of the multi-nozzle jethead unit having several multi-nozzle jet heads arranged apart from eachother;

[0070]FIG. 28 illustrates the relation between the carriage movingdirection and the nozzle arrangement of the jet head when themulti-nozzle jet head unit moves along with the motion of the carriage,while ejecting a solution containing a functional material;

[0071]FIG. 29 illustrates another example of the nozzle arrangement, inwhich the direction of multi-nozzle arrangement is parallel to thecarriage moving direction;

[0072]FIG. 30 illustrates still another example of the nozzlearrangement, in which the direction of multi-nozzle arrangement in thestacked jet head unit is parallel to the carriage moving direction;

[0073]FIG. 31A is a plan view of the functional device mounting boardhaving a group of functional devices in the functional device formingarea, while some figures are formed outside the functional deviceforming area. An example of the functional device is shown in FIG. 31Bformed by the jet head shown in FIG. 31C;

[0074]FIG. 32 is a plan view of another example of the functional devicemounting board having a group of functional devices in the functionaldevice forming area, while a performance check pattern is formed outsidethe functional device forming area;

[0075]FIG. 33 is a plan view of still another example of the functionaldevice mounting board having a group of functional devices in thefunctional device forming area, while a second group of functionaldevices is formed outside the functional device forming area;

[0076]FIG. 34 is a side view of the fabrication apparatus for afunctional device mounting board, having a-reliable solution supplysystem according to an embodiment of the invention, showing thepositional relation of the major units;

[0077]FIG. 35 illustrates an example of solution supply cartridgeaccording to an embodiment of the invention;

[0078]FIG. 36 illustrates how the solution supply cartridge is used inthe fabrication apparatus;

[0079]FIG. 37 illustrates the solution supply cartridge fit into thefabrication apparatus;

[0080]FIG. 38 is a side view of another type of fabrication apparatushaving a solution supply system, showing another arrangement of themajor units;

[0081]FIG. 39 illustrates an example of the ejection system according toan embodiment of the invention;

[0082]FIG. 40 illustrates another example of the ejection system;

[0083]FIG. 41A and FIG. 41B illustrate how the droplet is ejected fromthe nozzle;

[0084]FIG. 42 is a cross-sectional view of the jet head having a filteraccording to an embodiment of the invention;

[0085]FIG. 43 illustrates a fabrication apparatus for a functionaldevice mounting board, having ejector maintenance equipment according toan embodiment of the invention;

[0086]FIG. 44A and FIG. 44B illustrate an example of the ejectormaintenance equipment;

[0087]FIG. 45 illustrates an example of the nozzle suction unit providedto the ejector maintenance equipment;

[0088]FIG. 46A and FIG. 46B illustrate the nozzle of the jet head, whichis fit into the suction hole of the ejector maintenance equipment;

[0089]FIG. 47 illustrates how the solution is evacuated from the nozzleby the nozzle suction unit shown in FIG. 45;

[0090]FIG. 48A and FIG. 48B illustrate another example of thefabrication apparatus having ejector maintenance equipment thatfunctions inside the droplet ejection area;

[0091]FIG. 49 illustrates an example of the system for fabricating afunctional device mounting board, the system including the fabricationapparatus;

[0092]FIG. 50 illustrates an example of the jet head having a clean airsupply unit

[0093]FIG. 51 illustrates an example of the organic EL display boardfabricated by the fabrication apparatus according to the invention,which is used in a flat state;

[0094]FIG. 52 illustrates an example of the organic EL display board,which is bent in a convex state toward the viewer;

[0095]FIG. 53 illustrates an example of the organic EL display board,which is bent in a concave state with respect to the viewer;

[0096]FIG. 54A and FIG. 54B illustrate how the organic EL display boardis held by a guide having a curved guide groove; and

[0097]FIG. 55A and FIG. 55B illustrate examples of the combination ofthe organic EL display board and the cover plate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0098] The details of the present invention will now be described withreference to the attached drawings.

[0099]FIG. 1 illustrates fabrication of organic EL devices as an exampleof the functional devices. In this example, solution 2, in which organicEL material that emits light of red, green, or blue is dissolved, isejected from a nozzle 1 onto an ITO (indium tin oxide) transparentelectrode patterns 4 formed on glass substrate 5. The glass substrate 5has a barrier wall 3 that defines an array of the transparent electrodepattern 4, and the organic EL devices of the corresponding colors ofred, green, and blue are arranged as a mosaic pattern. The compositionof the solution 2 is as given below:

[0100] Solvent: dodecylbenzene/dichlorobenzene (1/1, volume ratio)

[0101] Red: polyfluorene/perylene dye (98/2, weight ratio)

[0102] Green: polyfluorene/coumarin dye (98.5/1.5, weight ratio)

[0103] Blue: polyfluorene

[0104] The ratio of the solid material to solvent is given as 0.4%(weight/volume). The substrate on which such solution has been appliedis heated at, for example, 100° C. to remove the solvent. Then, anappropriate metallic mask is formed on the substrate, and an aluminumlayer is formed by vapor deposition up to the thickness of 200 nm (notshown in the drawings). Lead wires are extended out from ITO andaluminum, whereby a device having an ITO anode electrode and an aluminumcathode is completed. Under the application of voltage of approximately15 volts, the device emits light of red, green or blue.

[0105] The electrodes may be formed on the substrate in advance, priorto ejecting droplets of the solution. The functional device is formed byletting the volatile ingredient of the solution vaporize such that solidingredients remain on the substrate.

[0106] By placing a transparent cover plate made of glass or plasticover the substrate opposing the functional devices, and then enclosing(packaging) it, an image display device, such as a spontaneous luminousorganic EL display, can be provided.

[0107] The functional device is not limited to an organic EL device. Forexample, an organic transistor or the like may also be suitablyfabricated as the functional device by applying the techniques of thepresent invention. Resist can also be used as the solution containing afunctional material applied onto the substrate in forming the barrierwall 3 of the above-described example.

[0108] In the present invention, inkjet techniques are applied as meansfor applying the solution containing a functional material. Specificexamples' of application of the inkjet techniques will be describedbelow.

[0109]FIG. 2 is a diagram for describing an embodiment of thefabrication apparatus for the functional device mounting board of thepresent invention. In this diagram, reference numeral 11 denotes a jethead unit (jet head); 12 denotes a carriage; 13 denotes a substratesupport bench (or a substrate holder); 14 denotes a substrate on which afunctional device is to be formed; 15 denotes a supply tube for thesolution that includes functional material; 16 denotes a signal supplycable; 17 denotes a jet head control box; 18 denotes an X-directionscanning motor for the carriage 12; 19 denotes a Y-direction scanningmotor for the carriage 12; 20 denotes a computer; 21 denotes a controlbox; and 22 (22X₁, 22Y₁, 22X₂, 22Y₂) denotes substratepositioning/holding means.

[0110]FIG. 3 is a schematic diagram illustrating the configuration of adroplet applicator used to fabricate the functional device mountingboard of the present invention; and FIG. 4 is a schematic diagram of theprinciple parts of the droplet applicator jet head unit in FIG. 3. Theconfiguration in FIG. 3 differs from that in FIG. 2, where a functionaldevice group is formed on the substrate by making the substrate 14 sidemove. In FIG. 3 and FIG. 4, a jet head unit 31 is a head alignmentcontrol mechanism, 32 is a detection optical system, 33 is an inkjethead, 34 is a fine head alignment mechanism, 35 is a control computer,36 is an image identification mechanism, 37 is an XY direction scanmechanism, 38 is a position detection mechanism, 39 is a positionalcorrection control mechanism, 40 is an inkjet head drive/controlmechanism, 41 is an optical axis, 42 are device electrodes, 43 is adroplet, and 44 is a location for droplet impact. Any appropriatemechanism may be used as the droplet applicator (inkjet head 33) in thejet head unit 11 as long as it can eject fixed quantities of arbitrarydroplets, however, a mechanism based on inkjet techniques that iscapable of forming droplets ranging from several to several hundreds plis especially preferable.

[0111] There are many inkjet methods. For example, an electrical signalis applied to a piezoelectric vibrator so as to convert the electricalsignal into mechanical vibration of a piezoelectric vibrator, whichcauses a droplet to be ejected from a minute nozzle. This method isdisclosed in U.S. Pat. Nos. 3,683,212 (Zoltan method), U.S. Pat. No.3,747,120 (Stemme method), and U.S. Pat. No. 3,946,398 (Kyser method).This is generally known as a drop-on-demand method.

[0112] Another method (the Sweet method) is disclosed in, for example,U.S. Pat. Nos. 3,596,275 and 3,298,030. In this method, a droplet of arecording fluid containing a controlled amount of electrostatic chargeis produced using a continuous vibration generating technique. Theproduced droplet of the recording fluid flies between polarizingelectrodes under the application of a uniform electric field, so as toreproduce images on a recording member. This is generally called thecontinuous flow method, or charge control method.

[0113] Yet another method is disclosed in Japanese Patent Publicationafter Examination (Koukoku) No. 56-9429. In this method, air bubbles aregenerated in the fluid, and the bubbles act on the fluid so as to causea droplet to be ejected from a minute nozzle. This technique isgenerally called the thermal inkjet method or bubble inkjet method.

[0114] Among these methods, including the drop-on-demand, the continuousflow method, and the thermal inkjet method, any appropriate method canbe chosen in accordance with needs. According to the present invention,an apparatus for fabricating a functional device mounting board (FIG. 2)is used. The holding position of the substrate 14 is fixed by thesubstrate positioning/holding means 22 for adjusting and determining thesubstrate holding position. As shown simplified in FIG. 2, the substratepositioning/holding means 22 makes contact with each side of thesubstrate 14, and is capable of making fine adjustments on the order ofmicrons in the X-direction and the Y-direction. The substratepositioning/holding means 22 is connected to a jet head control box 17,computer 20, and control box 21, thereby allowing for constant feedbackof the substrate positioning information, as well as fine adjustmentdisplacement information, droplet positioning information, and ejectiontiming.

[0115] Moreover, in addition to the X/Y direction position adjustmentmechanism, the fabrication apparatus for the functional device mountingboard has a rotational position adjustment mechanism although it is notshown in the drawings (because it is positioned beneath the substrate14). In connection with this, the shape of the functional devicemounting board and array of the functional device group will bedescribed first.

[0116] Any of silica glass, glass with a reduced impurity content of Naor the like, blue plate glass, a glass substrate with a SiO₂ layer, or aceramics substrate of alumina may be used as the substrate of thefunctional device mounting board of the present invention. Furthermore,various types of plastic substrates including PET may also be suitablyused for the purpose of reducing the weight and increasing flexibility.In any case, the substrate is rectangular, unlike silicon wafers, inview of economical production and supply, and of practical use of thefinal product (that is, functional device mounting board). Accordingly,the substrate has two vertical sides parallel to each other and twohorizontal sides parallel to each other, which configure a rectangularshape. A vertical side and a horizontal side make a right angle.

[0117] A group of functional devices are arranged in a matrix on therectangular substrate so that the two mutually orthogonal directions ofthis matrix are parallel to the directions of the vertical sides and thehorizontal sides of this substrate, respectively (see FIG. 31 throughFIG. 33). The reasons for this arrangement (i.e., arraying thefunctional devices in a matrix and making the vertical and horizontalsides of the substrate parallel with the two orthogonal directions ofthat matrix) will be explained below.

[0118] As illustrated in FIG. 2 or FIG. 3, once the position of thesolution ejecting surface of the jet head unit 11 with respect to thesubstrate 14 is determined, no particular positional control isrequired. The jet head unit 11 ejects the solution (for example,photoresist material, a solution of dissolved organic EL material, orconductive material), while moving in the X and Y directions relative tothe substrate so as to keep parallel to the functional device formingsurface with a fixed distance from the substrate 14. Basically, theX-direction and Y-direction are two mutually orthogonal directions. Bysetting the vertical side or the horizontal side of the substrateparallel to the Y-direction or X-direction during the positioning, agroup of functional devices can be formed precisely using a mechanism ofejecting the solution and a mechanism of causing relative displacement,because the two directions of the matrix array of the functional deviceare also parallel to the sides of the substrate. In other words, using arectangular substrate and the relative displacement mechanism in the Xand Y directions, and setting the array of the functional devices sothat the sides of the array are parallel to the sides of the substrate,allow a matrix of functional devices to be formed at high precision byaccurately positioning the substrate prior to ejecting droplets onto thesubstrate.

[0119] The rotational position adjustment mechanism mentioned earlier isnow described. As previously mentioned, the present invention aims toprovide a highly-precise functional device matrix array by accuratelypositioning the substrate before the ejection of droplets onto thesubstrate, and by causing relative displacement in the X and Ydirections without executing additional control operations. Whencarrying out initial positioning of the substrate, there may be anoffset (or positional shift) existing in the rotational direction aboutthe Z-axis perpendicular to the plane defined by the X and Y directions.In order to compensate for this rotational offset, a rotational positionadjustment mechanism (not shown in the drawings since it is positionedbeneath the substrate 14) is provided to the fabrication apparatus. Bycompensating the rotational deviation and by correctly positioning thesubstrate, a highly precise matrix array of functional devices can beobtained simply by the relative displacement in the X and Y directions.

[0120] In the above-described example, the rotational positionadjustment mechanism has been described as a separate mechanism from thesubstrate positioning/holding means 22 (22X₁, 22Y₁, 22X₂, 22Y₂) of FIG.2 (not visible since positioned beneath the substrate 14). However, thesubstrate positioning/holding means 22 may include the rotationalposition adjustment mechanism. For example, the substratepositioning/holding means 22 makes contact with the sides of thesubstrate 14, and the whole substrate positioning/holding means 22 ismade capable of adjusting the position in the X-direction andY-direction. In this case, angle adjustment can be conducted byproviding two screws positioned apart from each other and movableindependently of each other to each of the substrate positioning/holdingmeans 22 that receive one of the sides of the substrate 14. Therotational position control information is supplied to the jet headcontrol box 17, computer 20, and control box 21, together with the X, Ydirection positioning information and fine adjustment displacementinformation. This arrangement allows for constant feedback of dropletpositioning information and ejection timing information to the substratepositioning mechanism.

[0121] Next, another configuration of the positioning means will bedescribed. The substrate positioning/holding means 22 of the abovedescription makes contact with the sides of the substrate 14, and theentirety of the substrate positioning/holding means 22 is capable ofadjusting the position of the substrate in the X-direction andY-direction. Instead of making use of the sides of the substrate,strip-shaped patterns extending in two perpendicular directions may beformed on the substrate 14. As previously mentioned, the functionaldevice array is formed as a matrix. Accordingly, the strip-shapedpatterns extending in two perpendicular directions are set parallel tothe two mutually orthogonal sides of the matrix. Such patterns can beeasily formed on the substrate using a photofabrication technique.

[0122] Instead of forming the strip-shaped patterns separately only forthe-purpose of positioning, device electrodes 42 (FIG. 4) or the wiringpatterns extending in the X-direction and Y direction may be used as thepositioning strip patterns. Such strip-shaped patterns can be detectedby a detection optical system 32 using a CCD camera and lens, which willbe described with reference to FIG. 4 below, and the detectedinformation can be fed back to the positional adjustment.

[0123] Concerning the Z direction perpendicular to the X-Y plane, thepositional control is not particularly necessary in the Z direction oncethe positional relationship between the solution ejecting face of thejet head unit 11 and the substrate 14 is initially determined. Namely,the jet head unit 11 ejects the solution containing a functionalmaterial, while it moves relative to the substrate 14 in the X and Ydirections maintaining a fixed distance from the substrate 14.Positional control of the jet head unit 11 in the Z direction is notperformed during the ejection to prevent the associated mechanisms andthe control system from becoming complex. In addition, if positionaladjustment is carried out in the Z direction during the ejection, ittakes a longer time to form the functional device on the substratethrough application of droplets, resulting in reduced productivity.

[0124] Instead of performing positional control in the Z directionduring the ejection, the levelness of the substrate 14 and the substratesupport means is improved, as well as improving the precision of acarriage mechanism that drives the jet head unit 11 relative to thesubstrate 14 in the X, Y directions. The productivity is enhanced byincreasing the rate of the relative displacement between the jet headunit 11 and substrate 14 in the X, Y directions, even without performingpositional control in the Z direction during ejection. To give anexample, fluctuation in distance between the substrate 14 and thesolution ejecting surface of the jet head unit 11 during the ejection ofthe droplets is kept within 5 mm (in the case where the size of thesubstrate 14 is at least 200 mm×200 mm and smaller than 4000 mm×4000mm).

[0125] A plane defined by the X and Y directions is generally heldhorizontal. However, if the substrate 14 is small (for example, whensmaller than 500 mm×500 mm), the X-Y plane is not necessarily heldhorizontal, but should be set so that the positional relationship makesthe substrate 14 be located most efficiently for that device.

[0126]FIG. 3 illustrates another example of the present invention. Thepresent invention is not limited to this example. Unlike in FIG. 2, thesubstrate 14 is driven relative to the fixed jet head unit 31 whenfabricating a functional device mounting board. FIG. 4 is an enlargeddiagram of the jet head unit 11 shown in FIG. 3. To begin with, in FIG.3, reference numeral 37 denotes the XY direction scan mechanism uponwhich the functional device mounting board 14 is placed and held. Thefunctional device formed on the substrate 14 has the same configurationas that shown in FIG. 1. Each functional device is configured by theglass substrate 5 (equivalent to the substrate 14), the barrier wall 3,and the ITO transparent electrodes 4, as in FIG. 1. The jet head unit 11for ejecting droplets is positioned above the substrate (or functionaldevice mounting board) 14. In this example, the jet head unit 11 isfixed. By moving the functional device mounting board 14 to an arbitraryposition by the XY direction scan mechanism, relative displacementbetween the jet head unit 11 and functional device mounting board 14 isimplemented.

[0127]FIG. 4 illustrates the configuration of the jet head unit 11. InFIG. 4, reference numeral 32 denotes the detection optical system thattakes in the image information of the top face of the substrate 14. Thedetection optical system 32 is adjacent to the inkjet head 33 thatejects the droplet 43, and is arranged so that the optical axis 41 andfocal point of the detection optical system 32 coincides with thelocation of impact 44 of the droplet 43 through the inkjet head 33. Inthis case, the positional relationship between the detection opticalsystem 32 and inkjet head 33 illustrated in FIG. 3 can be preciselyadjusted via the fine head alignment mechanism 34 and head alignmentcontrol mechanism 31. Furthermore, a CCD camera and lens are used forthe detection optical system 32.

[0128] In FIG. 3, the reference numeral 36 denotes the imageidentification mechanism, which identifies the image informationdetected by the detection optical system 32. The image identificationmechanism 36 converts image contrast into binary data, and calculatesthe center of balance of a specific portion of the binary contrast.Specifically, the high-resolution image recognition device VX-4210manufactured by Keyence Corporation may be used. A position detectionmechanism 14 provides the position information existing on the substrate14 to the image information obtained by the image identificationmechanism. Length measuring equipment, such as a linear encoder,furnished in the XY direction scan mechanism 37 may be utilized here.The positional correction control mechanism 39 performs positionalcorrection based upon the positional information on the functionaldevice mounting board 14 and image information, whereby movement of theXY direction scan mechanism 37 is corrected. The inkjet head 33 isdriven by the inkjet head control/drive mechanism 40, whereby thedroplet is applied onto the functional device mounting board 14. Each ofthe control mechanisms mentioned thus far are centrally controlled bythe control computer 35.

[0129] In this example, the jet head unit 11 is fixed, while relativedisplacement between the jet head unit 11 and functional device mountingboard 14 is implemented through the motion of the functional devicemounting board 14 to an arbitrary position by means of the XY directionscan mechanism. Needless to say, however, as illustrated in FIG. 2, thefunctional device mounting board 14 may be fixed, while driving the jethead unit 11 in the X and Y directions. Particularly in cases ofapplying in manufacture of midsize substrates 200 mm×200 mm to largesize substrates of 2000 mm×2000 mm or larger, the latter structure ispreferable, where the functional device mounting board 14 is fixed,while driving the jet head unit 11 scans in the two orthogonal X and Ydirections. In this case, droplets of the solution are also ejectedalong the X direction and Y direction.

[0130] In contrast, if a light plastic substrate is utilized, or if thesize of the substrate is relatively small (100 mm×100 mm through 800mm×800 mm), paper feeding for a inkjet printer may be used. In thiscase, the jet head unit 11 mounted on the carriage 12 scans only in theX direction (or only in the Y direction), while the substrate is movedin the Y direction (or X direction). This arrangement can greatlyimprove the productivity.

[0131] In cases where substrate size is 200 mm×200 mm or smaller, thejet head unit for ejecting droplet is designed as a large-arraymulti-nozzle jet head unit capable of covering a range of 200 mm, so asto allow the relative displacement between the jet head unit and thesubstrate in only one direction (for example, only the X direction),instead of moving in two orthogonal directions (X and Y directions).This arrangement can achieve high mass productivity. If the substratesize exceeds 200 mm×200 mm, it is difficult to manufacture such alarge-array multi-nozzle jet head unit capable of covering the rangebeyond 200 mm from the standpoint of the cost and the technical aspect.In this case, the jet head unit 11 is designed so as to scan in the twoorthogonal X and Y directions to eject droplets of the solution in X andY directions alternately Particularly, when manufacturing a substratesmaller than 200 mm×200 mm by cutting a large substrate of 400 mm×400 mmthrough 2000 mm×2000 mm or larger, the array of the functional devicesis formed on such a large substrate using the inkjet technique.Accordingly, it is preferable for the jet head unit 11 to scan in thetwo orthogonal X and Y directions alternately to eject solution dropletsonto predetermined positions on the substrate.

[0132] As material for the droplet 43, apart from the previouslymentioned organic EL material, polyphenylene vinylene based elements(poly (paraphenylenevinylene) based derivatives), polyphenylene basedderivatives, or otherwise material such as low molecular weight organicEL material soluble in benzene derivatives, high molecular weightorganic EL material, or polyvinyl carbazole, for example, may be used.Rubrene, perylene, 9, 10-diphenyl anthracene, tetraphenyl butadiene,Nile red, coumarin 6, quinacridone, polythiophene derivatives and thelike can be given as specific examples of the organic EL material.Furthermore, charge carrying and hole carrying type material, which isperipheral material in organic EL display, is utilized as the functionalmaterial for manufacturing the functional device of the presentinvention.

[0133] Otherwise, a precursor of the silicon glass for interlayerinsulating film used in esemiconductor devices, or silica glass formingmaterial can be given as additional examples of the functional materialfor manufacturing the functional device of the present invention.Polysilazane (manufactured by Tonen Corporation, for example), organicSOG material and the like may be given as examples of this precursor. Anorganic metallic compound may also be alternatively used. Moreover,color filter material may be given as yet another example. Specifically,sublimated dye such as Sumikaron Red B (trade name, dye manufactured bySumitomo Chemical Co., Ltd.), Kayalon Fast Yellow GL (trade name, dyemanufactured by Nippon Kayaku Co., Ltd.) and Diethylene Fast BrilliantBlue B (trade name, dye manufactured by Mitsubishi Kasei Corporation)and the like may be used.

[0134] Regarding the solution composition of the present invention, itis preferable that the boiling point of the benzene derivatives be 150°C. or higher o-dichlorobenzene, m-dichlorobenzene,1,2,3-trichlorobenzene, o-chlorotoluene, p-chlorotoluene,1-chloronaphthalene, bromobenzene, o-dibromobenzene, and1-dibromonaphthalene can be given as specific examples of such solvent.Sublimation of the solvent can be prevented by using these solvents,thus are preferable. These solvents have a high degree of solubility inaromatic compounds, thus they are preferable. Furthermore, it ispreferable that the solution composition of the present inventionincludes dodecylbenzene. N-dodecylbenzene independently or an isomericcompound thereof may also be used as the dodecylbenzene.

[0135] This solvent has the characteristics of a boiling point at 300°C. or higher, and viscosity of 6 cp or greater (at 20° C.). The solventmay be used individually, or alternatively, it may be added to anothersolvent. In the latter case, sublimation of another solvent may beeffectively prevented. Furthermore, since the viscosity of the abovesolvents with the exception of dodecylbenzene is relatively small, theviscosity may be adjusted by adding this solvent, and it is thussuitable. According to the present invention, after such solutioncomposition is applied onto the substrate using the jet head, thesubstrate is processed at a temperature higher than the ejectiontemperature to make the droplets of the solution into a stable film ofthe functional material. The ejection temperature is generally roomtemperature, and therefore, the substrate bearing the solution dropletsis heated. The heating process allows the ingredient educed due toevaporation of the droplet during the ejection or a fall of thetemperature, to be re-dissolved, and therefore, a homogeneous, uniformfunctional film can be obtained.

[0136] It is preferable to heat the substrate bearing the droplet of thefunctional material under pressure. Heating under pressure delaysevaporation of the solvent, and promotes re-dissolving of the educedingredient. Consequently, a homogeneous and uniform functional film canbe obtained. Furthermore, with the manufacturing method of the abovefunctional film, it is preferable to reduce the pressure immediatelyafter high-temperature processing of the aforementioned substrate.Reducing the pressure immediately after the heating process can preventphase separation of the solvent during the solidification of thesolvent.

[0137] With any one of the above-mentioned materials or functionaldevices, the present invention performs device formation by evaporatingthe volatile component in the solution so as to leave the solid contenton the substrate. This solid component exhibits the functions of theassociated devices. The solvent (volatile component) is a vehicle forallowing the solution to be ejected using the inkjet technique.

[0138] In order to apply the droplet 43 onto a desired device electrodethrough the jet head unit (jet head) 11, the target position is measuredby the detection optical system 32 and image identifying device 36.Then, the corrected coordinates are generated based on the measureddata, the distance from the ejection outlet surface of the jet head unit(jet head) 11 to the functional device mounting board 14, and thecarriage moving speed. The jet head unit (jet head) 11 is moved acrossthe functional device mounting board 14 in the X and Y directions inaccordance with these corrected coordinates, while ejecting thedroplets. A CCD camera and the like may be used in combination with alens as the detection optical system 32. A commercially available devicethat can convert an image into binary data so as to obtain the center ofbalance of the image may be used as the image identifying device 36.

[0139] As can be clearly understood from the above description, thefunctional device mounting board of the present invention is fabricatedby ejecting the solution containing a functional material through theair onto the substrate using the inkjet technique.

[0140] Next, another feature of the present invention will be described.Especially, explanation will be made on the characteristics of thesubstrate required to fabricate a functional device mounting board athigh precision using the fabrication apparatus described above, as wellas the handling of such a substrate.

[0141] In order to precisely form a functional device in a reliablemanner, dot formation on the substrate is important. It is necessary toform a clear and round dot having a designed diameter on the substrate,without spreading or running of the droplet on the substrate.

[0142] Generally with the inkjet recording technique for ejecting ink onpaper, special inkjet recording paper, so-called coated paper, coatedwith silica or similar material is used for the purpose of forming around dot on the paper to obtain a dot with intended clear dimensions.The present invention concerns functional device mounting boards, ratherthan recording paper, and therefore, the structure of inkjet recordingpaper cannot be employed as it is.

[0143] Nonetheless, inspired by special inkjet recording paper, theinventors believe that with the functional device mounting board of thepresent invention, the condition of the substrate surface prior todepositing the droplet containing a functional material using the inkjettechnique greatly affects the shape (or the roundness) and size of thedot on the substrate. Especially, the roughness of the substrate surfaceis an important factor.

[0144] As previously mentioned, glass or ceramics is used as thesubstrate. If the glass surface is in a condition similar to groundglass, upon the application of the droplet of solution containing afunctional material onto the substrate through the inkjet technique, thesolution spreads rapidly due to the capillary phenomenon. The dropletcannot maintain the desired round shape.

[0145] Focusing attention on this phenomenon, through variously changingthe roughness of the surface of the substrate utilized for the presentinvention, the inventors experimentally considered what degree ofroughness is optimum so as to prevent the droplet spreading, avoiding aspread-out state. Results thereof are given hereinafter.

[0146] Silica glass plates and alumina substrates with SiO₂ deposited onthe surface (referred to as SiO₂ alumina substrate) were prepared forthe experiment. With the former one (silica glass), the surfaceroughness was varied ranging from a mirror-smooth state to aground-glass state. With the latter one (SiO₂ alumina substrate), thesurface roughness of the alumina substrate was set as smooth aspossible, and the volume condition of the SiO₂ to be sputtered on thealumina surface was changed so as to vary the surface roughness of theSiO₂ layer. The surface roughness was measured with a surface profilermanufactured by Dektak.

[0147] These substrates have been examined for conditions of favorabledot formation, using the fabrication apparatus illustrated in FIG. 2 toeject a droplet of solution containing a functional material by theinkjet technique.

[0148] The conditions for the solutions and the jet head used in theexperiment are given below.

[0149] The solution was a mixed solution of o-dichlorobenzene anddodecylbenzene, mixed with 0.1 weight percent poly (hexyl-oxiphenylenevinylene).

[0150] The jet head used in the experiment is a drop-on-demand typeinkjet head (see FIG. 41 and FIG. 42) utilizing piezo elements. Thenozzle diameter was set at 23 μm; the input voltage for the piezoelement was set at 27 V; and drive frequency was set at 12 kHz. Theinitial speed of the jet was 8 m/s. The mass of a droplet was 5 pl. Thecarriage scanning rate (in the X direction) was set at 5 m/s. Thedistance between the jet head nozzle and substrate was set at 3 mm.

[0151] A droplet was ejected under the same conditions as the actualdevice formation, while changing the waveform of the driving pulse. Thenthe shape of the flying droplet was observed. The driving waveform wascontrolled such that that shape of the flying droplet was nearly roundimmediately before reaching the substrate surface. When a perfectlyround spherical shape was not obtained, and instead, the droplet waselongated in the flying direction, then the drive waveform wascontrolled to keep the length of the elongated droplet within threetimes the diameter. Furthermore, drive conditions (drive waveform) werechosen so as not to produce minute trailing drops behind the flyingdroplet.

[0152] After the functional device if formed on the substrate throughthe ejection of droplets, aluminum was sputtered over the functionaldevice and the substrate. Lead wires were extended from the ITOelectrode and the aluminum layer, and a voltage of 10 volts was appliedbetween the ITO anode and aluminum cathode to estimate the deviceperformance. Table 1 shows the evaluation result.

[0153] In the table, the circle marked for the dot shape (or the dotspreading state) on the substrate represents satisfactory formation(clear dot without spreading) of dots, and therefore, the good formationof a functional device. The cross mark represents unsatisfactoryformation of a functional device due to slight spreading of thesolution, causing the unclear outline of the dot. The circle marked forthe device performance represents good emission of orange-color light ata prescribed shape, and the cross mark represents non-emission orpartial emission of orange-color light. The devices having suchimperfect light emission cannot be used as actual products. TABLE 1Substrate Dot formation Test surface state upon Device No. Substratetype roughness (S) substrate performance  1 Silica glass 0.05 ∘ ∘  2Silica glass 0.1 ∘ ∘  3 Silica glass 0.3 ∘ ∘  4 Silica glass 0.5 ∘ ∘  5Silica glass 0.8 x x  6 Silica glass 1.3 x x  7 Silica glass 2 x x  8PET film 0.2 ∘ ∘  9 PET film 0.3 ∘ ∘ 10 PET film 0.5 ∘ ∘ 11 PET film 0.8x x 12 PET film 1.3 x x 13 PET film 2 x x 14 SiO₂ alumina 0.2 ∘ ∘ 15SiO₂ alumina 0.5 ∘ ∘ 16 SiO₂ alumina 0.8 x x 17 SiO₂ alumina 1.2 x x

[0154] From the evaluation result, it is understood that, irrespectiveof substrate type, the dot formation on the substrate and the associateddevice performance greatly depend on the surface roughness of the areain which the dots of the solution are formed. When the surface roughnessof the substrate is 0.5 s or smaller, satisfactory shape of dots can beobtained on the substrate to form a functional device (an organic ELdevice, for example) suitable to practical use. On the other hand, ifthe surface roughness exceeds 0.5 s, dot formation on the substratebecomes unfavorable, causing a spread-out dot, and the resultantfunctional device is dissatisfactory and unsuitable for practical use.

[0155] It is understood that the surface roughness of the surface shouldbe set to 0.5 s or less in order to form a favorable functional device;however, there are a few problems.

[0156] The first problem is cost. In order to obtain such an extremelysmooth surface, the substrate needs to be polished with high precision.The same applies to the SiO₂ alumina substrate having a sputtered Sio₂layer on the alumina surface. It is necessary to take sufficient time toform a SiO₂ layer with a smooth surface, which causes the fabricationcost to increase.

[0157] Incidentally, through consideration of the functional devicemounting board of the present invention, the functional devices areformed on a single side of the substrate. This means that only one sideof the substrate requires a smooth surface, on which the functionaldevices are to be formed. As long as the device forming surface of thesubstrate has a roughness determined by the above-described experiment,the roughness of the rear face of the substrate may be greater than theabove-described value. By setting the surface roughness of only thedevice forming surface of the substrate at a prescribed range, a patternof the functional devices can be formed very precisely, whilemaintaining the fabrication cost low.

[0158] The second problem is tight contact between the fabricationapparatus and the substrate during the fabrication of a functionaldevice mounting board. If the substrate is held on the fabricationapparatus too tightly, the functional device mounting board cannot bedetached from the fabrication apparatus easily. In the first problem,the surface roughness is discussed from the viewpoint of the fabricationcost. In the second problem, the surface roughness is again focused onfrom the viewpoint of handling the substrate when removing thefunctional device mounting board from the fabrication apparatus. Duringthe experiment using the fabrication apparatus shown in FIG. 2, aproblem arose where the substrate adhered to the substrate support bench(or the substrate holder) 3 when the rear surface of the substrate wastoo smooth.

[0159] This problem resembles the principle of ringing where two blockgauges adhere to each other making use of the smoothness of thesurfaces. Through the experiment, it is known that if the back surfaceof the substrate is too smooth, it adheres to the substrate supportbench 13 and is difficult to remove, requiring extra efforts to removethe substrate from the apparatus. In this case, not only the productionyield is reduced, but also the operator or the worker may get hurt orotherwise, the functional device mounting board may be damaged, duringthe forcible removal of the functional device mounting board.

[0160] Then, another experiment was made by varying the surfaceroughness of the back surface of the respective substrates (i.e., silicaglass, PET film, and a SiO₂ alumina substrate) used in the previousexperiment to clarify at what degree of surface roughness removal of thesubstrate is facilitated without causing too tight contact between thesubstrate and the substrate support bench 13. The results are given inTable 2.

[0161] In Table 2, the circle marked for the easiness ofremoval/replacement of the substrate represents the case in which thesubstrate can be removed easily without undesirable contact between thesubstrate and the apparatus. The cross mark represents tight contactbetween the substrate and the apparatus, with difficulty in removal. Thesubstrate support bench 13 used in the apparatus has a surface obtainedby grinding and polishing SUS304. The back surface of the SiO₂ aluminasubstrate is not covered with a SiO₂ film, and the alumina surface isexposed. TABLE 2 Substrate Easiness of Test back surfaceremoval/replacement No. Substrate type roughness (S) of Substrate  1Silica glass 0.1 x  2 Silica glass 0.5 x  3 Silica glass 1 ∘  4 Silicaglass 1.5 ∘  5 Silica glass 3 ∘  6 PET film 0.5 x  7 PET film 1 ∘  8 PETfilm 1.5 ∘  9 PET film 3 ∘ 10 SiO₂ alumina 0.5 x 11 SiO₂ alumina 1 ∘ 12SiO₂ alumina 1.5 ∘ 13 SiO₂ alumina 3 ∘

[0162] As is clear from the experiment result, irrespective of substratetype, setting the roughness of the back surface of the substrate at 1 sor greater can overcome the problem of undesirable tight contact betweenthe substrate and the apparatus, which may cause the removal or thereplacement of the substrate to be difficult.

[0163] The problem of tight contact can also be resolved by othermeasures. One reason for the tight contact is a vacuum state causedbetween the back surface of the substrate and the substrate supportbench 13, which also resembles the principle of ringing (where two blockgauges used in precise measurement are attached together). To avoid thetoo tight contact, the vacuum state between the substrate and thesubstrate support bench 13 has to be avoided. FIG. 5 illustrates how thevacuum state is prevented.

[0164]FIG. 5A shows the back surface of the substrate (or the functionaldevice mounting board) 14, and FIG. 5B is a cross sectional view takenalong the B-B line shown in FIG. 5A. In this example, linear groves 14 aare formed in the back surface 14 ₁ of the substrate 14, which isopposite to the front surface 14 ₂ on which a group of functionaldevices are formed. Each of the grooves 14 a extends from one end to theother end of the substrate, forming cross stripes. In the example shownin FIG. 5, three grooves extend in each the vertical and horizontaldirections. The grooves 14 a function as air inlet channels that producean air layer between the substrate support bench 13 of the fabricationapparatus and the functional device mounting board. This arrangement canprevent the vacuum state.

[0165]FIG. 6 shows another example of the groove. FIG. 6A is a top viewof the back surface of the functional device mounting board 14, and FIG.6B is a cross sectional view taken along the B-B line shown in FIG. 6A.In this example, the groove has a V-shaped cross section, instead of aU-shaped cross section. Furthermore, only three vertical grooves areformed. The groove may have any shape in the present invention, as longas it functions as an air inlet channel to prevent tight contact betweenthe substrate 14 and the substrate support bench 13.

[0166] The groove can be formed in the back surface of the substrateusing a dicing saw or the like, as a secondary process. Thecross-section of the groove depends on the shape of the dicing blade,and therefore, the cross-sectional shape of the groove is arbitrary,including V-shape, U-shape, concave, or rectangular recess. A singleprocess of forming linear grooves using a simple tool, such as a diamondcutter, may also be employed, which is an even easier secondary process.

[0167] Besides the mechanical secondary process using a dicing saw orthe like, etching through a chemical process may be employed as thesecondary process when a glass substrate is used.

[0168] Since the groove can be formed in the back surface of thesubstrate very easily by a mechanical method with a simple tool, such asa diamond cutter or the like, or by a chemical process, such as etching,the cost for fabricating a functional device mounting board easy tohandle can be maintained low.

[0169] When using ceramics substrates, such as Al₂O₃ (alumina) or SiCsubstrates, the grooves may be formed through baking, by implementingpreparation for the groove prior to the baking process. In this case,the groove can be formed simultaneously with the production of theceramic substrate. The simultaneous formation of the grooves can also beapplied to a glass substrate. In this case, physical linear grooves areformed simultaneously when the external shape of the substrate isdefined using a press machine or a stamping machine. Such simultaneousformation of the grooves carried out during the process of forming asubstrate allows the process cost to be maintained low.

[0170] It is preferable to form several grooves in the substrate. Asingle groove does not exhibit sufficient effect. Multiple grooves canenhance the effect of producing the air path between the substrate andthe apparatus. Arranging the grooves in cross stripes as shown in FIG. 5is preferable. However, the grooves do not necessarily need to crosseach other at right angles.

[0171] In the examples illustrated in FIG. 5 and FIG. 6, the groovesextend parallel to the sides of the substrate. However, the groove mayextend obliquely at a certain angle with respect to the side of thesubstrate. In addition, the groove does not necessarily extend straight,and it may be curved. In any case, it is preferable for the groove toextend from one end to the other end of the substrate to let the airefficiently pass through the groove.

[0172] Regarding the dimensions of the groove, the depth and width maybe nearly the same. If the groove is too shallow, it becomes difficultfor the groove to perform the function of the air inlet channel. If thegroove is too deep, the substrate is likely to be damaged due toconcentration of the stress on the groove.

[0173] In view of the above points, another experiment was conducted toexamine the groove depth. The substrate used in the experiment is Pyrex(registered trademark) glass. The back surface of the Pyrex glass wasfinished to a roughness of 0.05 s, which is nearly a mirror surface. Agroove was formed in the mirror surface using a diamond cutter, whilechanging the depth. The substrate holder equivalent to the actualsubstrate support bench used in the apparatus is a SUS340 substrate,which was finished to a roughness of 0.05 s having a nearly mirrorsurface. The degree of easiness to place the substrate on the substrateholder (or the smooth slide of the substrate on the substrate holder)was observed. Three types of substrates having thickness of 2 mm, 4 mm,and 10 mm were prepared. The corresponding sizes are 420 mm×300 mm, 1200mm×800 mm, and 3500 mm×1800 mm, respectively. Each of the substrates hasthree rectangular grooves extending vertically and three rectangulargrooves extending horizontally, which grooves are arranged at a uniforminterval, as illustrated in FIG. 5. The observation result is givenbelow in Table 3, where groove width is set equal to the groove depth.

[0174] In the table, the circle represents smooth sliding of thesubstrate on the SUS340 substrate, which is a pseudo substrate supportbench, without causing the substrate to be stuck on the SUS340substrate. The cross mark represent the case where the substrate isstuck on the SUS340, or where the glass substrate is broken due toslight vibration during the experiment or transportation because thegroove is too deep, causing the mechanical strength of the glasssubstrate to be degraded. TABLE 3 Thickness Groove depth Evaluation t(mm) d (mm) t/d results  2 0.02 100 x (stuck)  0.04 50 ∘ 0.1 20 ∘ 0.2 10∘ 0.3 6.7 ∘ 0.4 5 ∘ 0.5 4 x (damage) 1 2 x (damage)  4 0.04 100 x(stuck)  0.06 67 x (stuck)  0.08 50 ∘ 0.1 40 ∘ 0.5 8 ∘ 0.8 5 ∘ 1 4 x(damage) 2 2 x (damage) 10 0.04 250 x (stuck)  0.08 125 x (stuck)  0.250 ∘ 0.5 20 ∘ 1 10 ∘ 1.3 7.8 ∘ 2 5 ∘ 3 3.3 x (damage) 5 2 x (damage)

[0175] According to the evaluation result, the lower limit of the groovedepth d should be at or greater than one fiftieth ({fraction (1/50)}) ofthe thickness t of the substrate. Below one fiftieth, the substrate willbe stuck on the substrate holder.

[0176] Regarding the upper limit, the groove depth d should be at orsmaller than one fifth (⅕) of the thickness t of the substrate. Ifexceeding the one fifth of the thickness t, the substrate is likely tobe damaged and is not suitable for practical use.

[0177] Instead of forming a groove in the substrate, a ridge or aprojection may be formed on the back surface of the substrate, asillustrated in FIG. 7.

[0178]FIG. 7A is a top view of the back surface of the functional devicemounting board 14, and FIG. 7B is a cross-sectional view taken along theB-B line shown in FIG. 7A. With this arrangement, the substrate 14 issupported above the substrate support bench 13 by means of ridges 14 cextending in the back surface plane 14 ₁. Accordingly, a thin layer ofair exists between the substrate 14 and the substrate support bench 13.In this manner, the substrate 14 can be prevented from being stuck ontothe substrate support bench 13. The cross-sectional shape of the ridge14 _(c) may be rectangular as in FIG. 7, or may be of any shape, such astriangular or semicircular.

[0179] The substrate 14 having a ridge or a protrusion 14 _(c) may beeasily formed through the aforementioned simultaneous formation of thesubstrate, as explained in conjunction with the groove formed in theback surface of the substrate. Namely, in the case of using ceramicssuch as Al₂O₃ (alumina) or SiC as the substrate, the ridge or theprotrusion can be simultaneously formed during the baking of thesubstrate by performing pre-treatment of the substrate so as to createthe ridge during the baking process. The simultaneous formation of theridges or the protrusions can also be applied to the glass substrate. Inthis case, physical linear protrusions are formed simultaneously whenthe external shape of the substrate is defined using a press machine ora stamping machine. Such simultaneous formation of the protrusion duringthe process of forming a substrate allows the process cost to bemaintained low.

[0180] By forming a groove or a protrusion in the back surface of thesubstrate, which is used to produce a functional device mounting board,a thin layer of air is created between the substrate and the substratesupport bench (or the substrate holder) to prevent the substrate frombeing stuck on the bench (holder). This arrangement can facilitateplacing or removing the substrate onto or from the substrate supportbench, while effectively preventing the tight contact or vacuum contactbetween the substrate and the substrate support bench.

[0181] Next, yet another feature of the present invention will bedescribed with reference to FIG. 8 through FIG. 13, where the shape ofthe corner or the edge of the substrate is modified. As has beendescribed above, the functional device mounting board of the presentinvention employs a rectangular substrate made of silica glass,impurity-reduced glass with reduced amount of Na or other impurities,blue plate glass, a glass substrate with SiO₂ layer on the top surface,a ceramic (including alumina) substrate with a SiO₂ layer on the topsurface, or any other suitable material. The two parallel vertical sidesand the two parallel horizontal sides configure the rectangular shape.The vertical and horizontal sides make a right angle.

[0182] Incidentally, such a rectangular substrate has four corners eachwith an angle of 90°. Since the substrate is made of glass, ceramics ora similar material, workers often accidentally get hurt during theprocess of fabricating the functional device mounting board.Consequently, with the present invention as illustrated in FIG. 8,corners of the substrate are chamfered as indicated by C1 in FIG. 8A, orrounded as indicated by R1 in FIG. 8B. Preferably, the chamfer is at orgreater than C1 or R1 illustrated in FIG. 8 so as to reduce thesharpness of the corner. This arrangement can prevent the workers frombeing hurt on the job (when transporting the substrate, removing orplacing the substrate from or onto the fabrication apparatus). Thecorners can be chamfered easily through a grinding process using agrinder containing abrasive grains, such as carborandom or emery.

[0183]FIG. 9 illustrates another example of the chamfered substrate. Inthis example, the right bottom corner C1 of the substrate 14 has adifferent shape of chamfer from the other three corners R1. Thisarrangement allows the orientation of the substrate to be easilydetermined when installing the substrate 14 onto the substrate supportbench 13 of the fabrication apparatus (see FIG. 2). By differing theshape of at least one corner (the angular portion) so as to bedistinguishable from the other corners, the workers can easily recognizethe orientation of the substrate during the fabrication of thefunctional device mounting board, and install the substrate correctly.It is preferable to set the size and the shape of each cornerdistinguishable from the other corners so as to allow a worker torecognize by touch. Such an arrangement can improve the efficiency insubstrate installation, while greatly reducing operational errors.

[0184]FIG. 10 illustrates yet another example of the substrate. In thisexample, at least one of the four sides of the substrate 14 is providedwith a notch or a cutaway L. Such a cutaway L also allows theorientation of the substrate to be correctly set when installing thesubstrate 14 onto the substrate support bench 13 of the fabricationapparatus shown in FIG. 2. The workers can determine the orientation ofthe substrate when installing the substrate onto the fabricationapparatus by simply touching the cutaway or the notch. This arrangementimproves the reliability of the substrate installation, while greatlyreducing operational errors. Although not shown in FIG. 2, a substratestopper may be provided to the substrate support bench 13 shown in FIG.2, so as to receive the cutaway L when the substrate is placed on thesubstrate support bench 13. Such arrangement secures accurateinstallation or accurate positioning of the substrate.

[0185]FIG. 11 illustrates yet another example of the substrate. Thisexample focuses on safe handling of the substrate, which is in favor ofthe workers during the process of fabricating the functional devicemounting board.

[0186] The functional device mounting board of the present inventionuses, as previously mentioned, silica glass, impurity-reduced glass witha reduced amount of Na and the like, blue plate glass, a glass substratewith a SiO₂ layer deposited on the surface, a ceramic substrate ofalumina or the like with a SiO₂ layer deposited on the surface, orvarious types of plastic substrates including PET. When handling such asubstrate to install the substrate on the fabrication apparatus (seeFIG. 2 and FIG. 3), to transport the substrate, or to incorporate thefunctional device mounting board into an image display apparatus (whichwill be described later), accidents often occur involving the workers,for example, cutting themselves on the edge of the substrate. This isbecause the material is glass or ceramics, and the edge or the rim ofthe substrate works as a sharp blade. Accordingly, the edges of thesubstrate are chamfered so as to reduce the sharpness in the exampleshown in FIG. 11.

[0187]FIG. 11A is a top view of the substrate 14, and FIG. 11B is across-sectional view taken-along the B-B line shown in FIG. 11A.Reference numeral 14 denotes a substrate on which a group of functionaldevices are to be formed, and is made of Pyrex (registered trademark)glass in this case. How the edges (i.e., the regions along the thicknessof the substrate) are processed for the safe handling is clearlyillustrated in the cross section of FIG. 11B. In this example, the edges(or the ridge lines) formed between the top surface 142 on which thefunctional devices are to be formed and the edge face 143 along thethickness of the substrate are chamfered as indicated by C1 and Cr.Similarly, the ridge lines formed between the back surface 14 ₁ and theedge surfaces 14 ₃ along the thickness are chamfered as indicated by C1and Cr.

[0188] As for the chamfer, the ridgelines are chamfered by specifyingthe degrees c_in mechanical drawings in the example shown in FIG. 11B;however, the chamfer may be defined by specifying the radius ofcurvature RXX in mechanical drawings. The edges (ridgelines) can bechamfered into any shape as long the edge of a right angle can beeliminated so as to prevent the edge from functioning as a sharp edge.This arrangement can effectively protect the workers from cuttingthemselves when touching the edges.

[0189]FIG. 12 is an enlarged diagram of the corner edge Q of thesubstrate shown in FIG. 1A. At the corner edge Q, two perpendicularchamfered edges C meet with each other to create an edge line D.

[0190]FIG. 13A and FIG. 13B illustrate yet other examples of edgeconfigurations. In the example shown in FIG. 13A, the corner edge Qshown in FIG. 12, at which the two perpendicular (vertical andhorizontal) chamfered edges meet with one another along the edge line D,is further chamfered to create a pentagonal chamfer E. In the exampleshown in FIG. 13B, the corner edge Q is further chamfered to create aquadrangular chamfer F at each of the four corners of the substrate 14.

[0191] By chamfering the substrate 14, accidents where workers cut theirhands with the edges of the substrate during the fabrication process ofthe functional device mounting board (including transporting, replacing,and removing the substrate onto or from the fabrication apparatus) canbe reduced. As illustrated in FIG. 13, not only the side edges of thesubstrate, but also the corner edges are chamfered to eliminate sharpedges, and accordingly, the safe operation of the workers is furtherguaranteed. In addition, the substrate with the side edges and thecorner edges chamfered as in the present invention is hardly damaged,unlike the conventional substrate with sharp edges made at a rightangle, even when the corner of the substrates hits against somethinghard. Consequently, the manufacturing yield is improved.

[0192] The side edges and the corner edges are easily chamfered orrounded off by using abrasive material such as emery or carborandom #100through #2000 or the like, or a grinding stone (grinder) made from theseabrasive materials pressed by a binder. If the shape of the edgeportions is rounded at a specific radius of curvature indicated by rXXin mechanical drawings, the grinder is shaped into a corresponding roundshape in advance so that the object (that is, the corner edge of thesubstrate) becomes a desired curvature. In this case, the target edge issimply rubbed against the rounded face of the grinder.

[0193] As to the surface roughness of a chamfered processed portion, itis preferable to make the chamfered surface rougher than the surfaceroughness of the top face of the substrate, on which a group offunctional devices are formed. The functional device forming surface isgenerally polished into a mirror-surface in order to guarantee theformation of precise and minute patterns. On the other hand, nofunctional device is formed at the chamfered portion, and therefore, itis unnecessary to make the chamfered portion excessively smooth. Rather,it is preferable to leave the chamfered portion rougher than thefunctional device forming area for the purpose of reducing thefabrication cost. Generally, the surface roughness of this chamferedportion is set from 0.5 s to 5 s.

[0194] As can be clearly understood from the above description, thefunctional device mounting board of the present invention preventsaccidents, and improves the yield during manufacturing by chamfering theside edges and/or the corner edges of the original substrate.

[0195] The foregoing is about the processing of the edges of thefunctional device mounting board; however, the edge processing isequally applied to the cover plate that covers the functional devicemounting board when manufacturing a display apparatus. It is alsodesirable to reduce accidents when the cover plate is handled duringassemble of the display apparatus. The cover plate is generally formedby glass or plastic, and preferably, the side edges and/or the corneredges of the cover plate are chamfered in the same manner as thefunctional device mounting board.

[0196] The workers are protected from unexpected accidents by chamferingthe edges extending along the sides of the top face or the edgesextending along the sides of the back face of the cover platelate, andsurfaces along the thickness and perpendicular to that front surface.The surface roughness of that chamfered portion of the cover plate ismade rougher than that of the top and back surfaces of the cover platefor the purpose of reducing the cost.

[0197] Since the cover plate is likely to receive external impacts, itrequires rigidity and durability. In the present invention, thethickness of the cover plate is made thicker than that of the functionaldevice mounting board in order to avoid damage to the functional devicemounting board due to accidental impact, which may be produced whenhitting the display apparatus against something hard. It is alsopreferable to use reinforced glass to increase the durability of thecover plate, which will be described later.

[0198]FIG. 14 illustrates another feature of the present invention. Thisexample shows how the substrate 14 is held on the substrate supportbench (or the substrate holder) 13 of the fabrication apparatus duringthe fabrication of the functional device mounting board. The substrate14 is held horizontally (at approximately 90 degrees with respect to thevertical direction in which gravity force works) with the top facefacing upward. The jet head 11 is placed above the substrate at distanceL from the top face of the substrate 14 so that droplet 43 of thesolution containing a functional material reaches the substrate 14 alongthe direction of gravity force, as indicate by the arrow. Thisarrangement is desired to preserve stable flying of the droplets and toguarantee accurate positioning of the droplets onto the substrate duringapplication of the solution droplets. By placing the substrate face up,while setting the flying direction of the droplets ejected from the jethead 11 in the direction of the gravity force, stable flying of droplets43 is achieved, allowing each droplet to reach the intended location onthe substrate 14.

[0199] In order to apply droplets accurately onto the target position onthe substrate, the precision and the mechanical strength of thelarge-screen substrates, to which the present invention is applied, havealso to be maintained. To this end, the thickness of the substrate usedin the present invention is set to 2 mm or greater.

[0200] As described earlier, a glass substrate such as silica glass,glass with reduced impurities (e.g., sodium (Na)), blue plate glass; orglass substrates covered with a SiO₂ layer, a ceramics-based substratesuch as alumina covered with a SiO₂ layer, or a similar substrate may beused as the substrate 14. In general, these materials are fragile, ascompared with metals, and easily damaged. Accordingly, the substratemade of these materials needs to have a certain degree of thick,otherwise the substrate may be broken during transportation or shipping.

[0201] Generally, blue plate glass has a bending strength of about 500kg/cm². It is preferable to produce reinforced glass having a bendingstrength of approximately 1500 kg/cm², using a glass strengtheningtechnique called air-cooling reinforcement, and to use such a reinforcedglass plate as the substrate 14. This technique is effectively appliedto a glass plate with a thickness ranging from 2 mm to 15 mm to increasethe bending strength up to approximately 1500 kg/cm². If the thicknessof the glass plate is less than 2 mm, bending strength of 1500 kg/cm²cannot be achieved; however, semi-reinforced glass can be produced byair-cooling reinforcement. The method for reinforcing the glass plate isnot limited to air-cooling reinforcement, and any other technique, suchas chemical reinforcement for giving compression strain to the surfaceof the glass plate through ion substitution, may be effectively used.

[0202] Since the functional device mounting board of the presentinvention is applicable to a high-quality and high-resolution imagedisplay apparatus, the accuracy in positioning the droplet at a preciseposition on the substrate is important. In order to achieve the highlyprecise positioning of droplet, deformation or warping of the substrate14 must be eliminated. Such deformation or warping also prevent thesubstrate 14 from being transported correctly.

[0203] The present invention may be favorably applied to medium screen(approximately 300 mm×450 mm) and large screen (approximately 2000mm×3000 mm) image display apparatuses. In these applications,degradation of the accuracy of the functional device due to deformationmust be prevented. In view of this requirement, it is preferable to setthe thickness of the substrate ranging from 2 mm to 15 mm. The lowerlimit of. 2 mm is the thickness that guarantees stable fabrication of areinforced glass plate in an ordinary manner.

[0204] Holding the substrate 14 horizontally (approximately at 90° withrespect to the vertical direction in which gravity force is applied)with the top face upward is effective to minimize deformation of thesubstrate 14 during fabrication of the functional device mounting board.FIG. 15 is a top view (in which the jet head is omitted) showing how thesubstrate 14 is placed on the substrate support bench (or holder) 13.The substrate 14 is held on the substrate holder 13 by surface contactwith the holder 13, without inclination or floating from the top face ofthe substrate holder 13. This arrangement allows even a large-sizedsubstrate applicable to medium screen (approximately 300 mm×450 mm) orlarge screen (up to approximately 2000 mm×3000 mm) image displayapparatuses to be held in a stable manner without causing the substrate14 to deform or bend due to its own weight. Consequently, highlyaccurate positioning of droplets 43 is achieved. The upper limit of thethickness of the substrate 14 is preferably set to 15 mm from thestandpoint of substrate manufacturing cost, as well as easiness forfabrication, handling, and transportation of the substrate.

[0205] Next, another feature of the present invention about the shapeand size of the droplet 43 will be described. As has been describedabove, a solution containing a functional material is applied to thesubstrate 14 by ejecting fluid droplets from the jet head 11. Thedroplet flies through the air toward the intended position on thesubstrate 14. When forming a functional device on the substrate 14making use of such an inkjet technique, stability in shape of thedroplet 43 during the flying through the air has to be consideredcarefully. If stable flying of droplet 43 is guaranteed, the positioningaccuracy of the droplet 43 onto the substrate 14 is also guaranteed. Incontrast, if the flying condition of the droplet 43 is unstable, thedroplet having reached the substrate is offset from the correctposition. During the ejection, the droplet 43 is likely to be affectedby disturbance or the air current in the air. Accordingly, it isnecessary to shut out such disturbances, or alternatively, to apply aforce so as to increase the stability in order to secure stable flyingof droplet 43.

[0206] The present invention takes the above points into consideration,and it was examined through testing what directionality the droplet 43should have when flying through the air and what length L the droplet 43should travel from the jet head 11 to the substrate 14 in order tosecure the stability required to form a functional device precisely. Theapparatus shown in FIG. 2 is used to moving the jet head 11 by acarriage in the scanning direction, while pushing the droplet to flythrough the air by means of liquid ejection of solution containing afunctional material.

[0207] In the example shown in FIG. 2, the substrate (or the functionaldevice mounting board) 14 is held horizontally, and the jet head 11mounted on a carriage is placed above the substrate 14 so that dropletsare ejected downward in the direction of gravity force. In this case,gravity force acts on the droplet and stabilizes the trajectory of theflying droplets. Consequently, the droplet flies onto the substrate in astable manner.

[0208] However, if the length L (see FIG. 14) from the ejecting surfaceof the jet head 11 to the substrate 14 is increased, time taken for thedroplet to fly to the substrate 14 becomes long. In this case, thedroplet is more likely to be affected by disturbance. Accordingly, theoptimum distance from the ejecting surface of the jet head 11 to thesubstrate 14 and the optimum-shape of the droplet in the air were foundthrough testing.

[0209] The experiment results are shown below. In the experiment, thesubstrate was held substantially horizontal and droplet 43 was ejecteddownward from the jet head 11, while varying the distance L from theejecting surface of the jet head 11 to the substrate to evaluate flyingstability of the droplet. Because flying stability cannot be observeddirectly, the shape of the droplet of solution containing the functionalmaterial on the substrate 14 was observed, and flying stability wasevaluated from the observed shape.

[0210] The conditions of the solution and the jet head used in theexperiment are indicated below.

[0211] The solution contained 0.1 weight percient (wt. %) solution ofpolyhexyl oxiphenylene vinylene mixed intoo-dichlorobenzene/dodecylbenzene solution.

[0212] The jet head used in the experiment is a drop-on-demand inkjethead using piezo elements. The nozzle size of the inkjet head was 23 μm,the input voltage to the piezo element was 26 V, and the drive frequencywas 9.6 kHz. Here the initial jet velocity of the droplet ejecteddownwards was 6 m/s, and the mass of one droplet was 5 μl. The carriagetraveling speed in the X direction was set to 5 m/s. The distancebetween the jet head 11 and the substrate 14 was 3 mm.

[0213] A droplet was ejected under the same conditions as the actualdevice formation, and the shape of the droplet during flying wasobserved. The driving waveform (or pulse form) was controlled so thatthe droplet became a substantially round shape immediately before thedroplet reached the substrate (in this example, after flying about 3mm). When a droplet became elongated along the path of flight, withoutforming a perfectly round shape, then the driving waveform wascontrolled so as to make the length of the droplet equal to or smallerthan three times the diameter. In addition, the driving condition (orthe driving waveform) was chosen such that there were no minute dropletstrailing behind the flying droplets.

[0214] Thereafter, aluminum was deposited upon this to carry out deviceformation. Lead lines of ITO and aluminum were extended with the ITOlines being positive-electrode and the aluminum lines being negative,and upon application of 10 volts, the results shown in table 4 wereobtained. This shows evaluation of the status of device formation uponthe substrate and device performance for different lengths L betweensurface of the jet aperture in the jet head and the substrate.

[0215] In this table, a circle mark for the status of device formationon the substrate represents the correct positioning of droplet at thetarget position (which is defined by the barrier walls 3 enclosed withpolyimide). A triangle represents the droplet partially offset from thetarget position. A cross mark represents the droplets offset from thetarget position. A circle for device performance denotes that aprescribed shape of orange-color light is emitted, and a cross markdenotes that the orange-color light is not emitted or only partiallyemitted (which means that the device is unsuitable for practical use).TABLE 4 Device formation Device L (mm) status performance 0.05 x x 0.1 ∘∘ 1 ∘ ∘ 2 ∘ ∘ 3 ∘ ∘ 4 ∘ ∘ 5 ∘ ∘ 6 ∘ ∘ 7 ∘ ∘ 8 ∘ ∘ 9 ∘ ∘ 10 ∘ ∘ 11 Δ x 12Δ x 13 x x

[0216] The above results show that when the length L from the surface ofthe jet aperture to the substrate was 0.05 mm, device formation wasunsatisfactory. This is because the ejecting surface having jetapertures was too close to the substrate, and therefore, the dropletreaches the substrate before separating from the jet aperture.

[0217] If the fluid was ejected substantially downward from the jethead, and if the length L between the surface of the jet aperture andthe substrate was set in the rage between 0.1 mm and 10 mm, thenfavorable device formation was achieved. If the length L was set largerthan 10 mm, satisfactory devices were not obtained. As the length Lincreases, the flying distance also increases, and the droplet is morelikely to be affected by disturbances.

[0218] In the present invention, droplets are ejected, while moving thecarriage that mounts the jet head 11 in order to improve theproductivity. The relative traveling speed between the jet head and thesubstrate (for example, the moving speed of the carriage in the Xdirection in FIG. 2) is determined not only from the viewpoint ofimproving the productivity, but also from the viewpoint of precisedevice formation on the substrate.

[0219] As a result of detailed study regarding the device formationusing an inkjet technique, it was found that the ejection speed of thedroplet has to be set greater than the relative traveling speed of thejet head 11. Since a droplet is ejected to form a functional device,while moving the jet head unit 11 in the X and Y directions relative tothe substrate 14 with a certain distance between them, the velocity ofthe droplet is defined as a composite vector of the ejection velocityand the relative traveling velocity of the jet head. As for thepositioning accuracy of the droplet, it is possible to control thedroplet so as to reach the target position by appropriately selectingthe jet timing, taking into consideration the distance between thefunctional device mounting board 14 and the surface of the fluid jetaperture in the jet head unit 11, and the velocity of the compositevector.

[0220] Nevertheless, even when the droplet is well-controlled so as toreach the intended location, if the relative velocity is too large, thedroplet may be pulled by the relative velocity and run on the functionaldevice mounting board. In this case, a group of functional devicescannot be fabricated in a precise shape of a matrix. The presentinvention incorporates consideration of this point. The results of thistesting are shown below. In this example, an apparatus shown in FIG. 2was used, and the traveling speed of the carriage 12 in the X-directionand the ejection speed of the jet head unit 11 were varied to studywhether or not the droplet reaches the substrate in good condition so asto work as the functional device.

[0221] The substrate 14 used in the experiment has polyamide embankments(barrier layer) 3 made on the glass substrate having ITO transparentelectrodes. The barrier layer 3 is formed by photolithography. Thefabrication apparatus shown in FIG. 2 was used, and a 0.1 wt. % solutionof polyhexyl oxiphenylene vinylene mixed ino-dichlorobenzene/dodecylbenzene mixed solution was ejected at differentejection velocities based on inkjet principles. The length between thejet head nozzle and the substrate was 3 mm.

[0222] The inkjet head used has a nozzle diameter of 25 μm and is adrop-on-demand inkjet head utilizing piezo elements, wherein the inputvoltage to the piezo element was varied from 18 V to 30 V in order tochange the ejection velocity. The drive frequency was given as 9.6 kHz.With such a drop-on-demand type inkjet head using piezo elements, theejection velocity can be changed by changing the voltage applied to thepiezo elements. However, since the mass of the ejected droplet alsochanges in accordance with the change in applied voltage, the drivewaveform (defined by the rising edge and the falling edge of the pulse,including for ejection while moving backwards) was adjusted so that themass of the jet droplet was always substantially constant (in this case,6 pl), and so that only the ejection velocity varied.

[0223] A fluid droplet 43 was separately ejected under the sameconditions as the actual device formation, and the shape of the dropletduring the flight was observed. Then, a droplet was ejected whilecontrolling the drive waveform so that the droplet became substantiallyround, as shown in FIG. 16, immediately before the droplet reached thesubstrate surface (in this example, after 3 mm flight). Even if aperfectly round sphere cannot be obtained, and instead, an elongateddroplet extending along the path of flight is obtained as shown in FIG.17, the length of the elongated droplet can be easily set equal to orsmaller than three times the diameter (L≦3d) simply by controlling thedriving waveform. The drive conditions (including the drive waveform)were chosen so that there were no minute droplets 43′ shown in FIG. 18trailing behind the flying droplet 43.

[0224] Aluminum was deposited thereupon to carry out device formation.Lead lines are formed extending from the ITO and aluminum to make theITO anode and make and the aluminum cathode, and a voltage of 10 voltswas applied. The results shown in table 5 were obtained. In this table,a circle marked for the status of device formation on the substratedenotes that droplet reached the target region (within the barrier walls3 enclosed with a polyimide), and cross mark denotes the droplet offsetfrom the target region. A circle marked for device performance denotesthat a predetermined shape of orange-color light is emitted, and a crossmark denotes that the orange-colored light is not emitted or onlypartially emitted (which is unsuitable for practical use). TABLE 5Carriage traveling Device Jet velocity in formation Test velocity Xdirection status upon Device No. Vj (m/s) Ve (m/s) substrate performance 1  2  1 ∘ ∘  2  2  2 x x  3  2  3 x x  4  4  1 ∘ ∘  5  4  2 ∘ ∘  6  4 3 ∘ ∘  7  4  4 x x  8  4  5 x x  9  6  2 ∘ ∘ 10  6  3 ∘ ∘ 11  6  4 ∘ ∘12  6  5 ∘ ∘ 13  6  6 x x 14  6  7 x x 15  6  8 x x 16 10  4 ∘ ∘ 17 10 6 ∘ ∘ 18 10  8 ∘ ∘ 19 10 10 x x 20 10 12 x x 21 10 14 x x

[0225] The above results show that favorable element formation cannot beachieved any longer when the traveling velocity of the carriage in theX-direction becomes equal to the jet velocity or exceeds it. To put itanother way, in the case of forming a functional device mounting boardusing a drop-on-demand inkjet head with piezo elements, the velocity ofthe fluid droplet 43 ejected from the jet head 11 must be set greaterthan the traveling velocity of the carriage 12 in the X-direction. By sosetting, an excellent functional device and an excellent functionaldevice mounting board can be obtained without any minute droplets 43′attached on the substrate because the droplet flight conditions arechosen so that no minute droplets 43′ are caused to trail behind theflying droplet 43.

[0226] A comparison experiment was made using a commercially availablemonochrome head mounted in a printer manufactured by Hewlett Packard andsold under the trade name of DeskJet 970 Cxi as the inkjet head. Themonochrome head was filled with the solution described above, instead ofink. The solution was ejected from the monochrome head to form afunctional device mounting board in the same manner in order to examinewhether or not the functional device formed on the substrate correctlyfunctions. With this monochrome head, the mass of the ejected dropletwas a substantially constant quantity of 6 pl. However, unlike thedrop-on-demand inkjet head using piezo elements, the shape of thedroplet was elongated too much (L=10*d to 20*d) along the direction offlight as shown in FIG. 18. In addition, lots of minute dropletsfollowed the flying droplet.

[0227] The monochrome head is of a thermal inkjet type, which isdifferent from the drop-on-demand type inkjet head using piezo elements.In the thermal inkjet head, a bubble is generated instantaneously in theliquid, which acts on the liquid to cause a droplet to be ejected fromthe inkjet head. There are two types of thermal inkjets, namely, a sideshooter, where a fluid droplet is jet in the same direction as the maindirection of growth of the bubble, and an edge shooter, where a fluiddroplet is jetted in a direction substantially perpendicular to the maindirection of growth of the bubble. The monochrome head used in thecomparison example is of the former type.

[0228] Nevertheless, regardless of the type of the thermal inkjetmethods, the ejection force caused by the bubble is too large becausethe bubble is generated near the ejection port of the nozzle, unlike thedrop-on-demand inkjet head. Accordingly, the droplet is excessivelyelongated accompanied by many particles (minute droplets), asillustrated in FIG. 18.

[0229] Table 6 shows the comparison results when the above-describedhead was used. The ejection velocity of the fluid droplet was changed byvarying the voltage applied to the heating element ranging from 22 V to23 V. TABLE 6 X direction carriage Device Spray traveling formation Testvelocity velocity status upon Device No. Vj (m/s) Vc (m/s) substratefunctioning  1  6  1 ∘ ∘  2  6  2 ∘ ∘  3  6  3 x x  4  6  4 x x  5  6  6x x  6  6  8 x x  7  6 10 x x  8  6 12 x x  9  6 14 x x 10  9  1 ∘ ∘ 11 9  2 ∘ ∘ 12  9  3 ∘ ∘ 13  9  4 x x 14  9  6 x x 15  9  8 x x 16  9 10 xx 17  9 12 x x 18  9 14 x x 19 12  1 ∘ ∘ 20 12  2 ∘ ∘ 21 12  3 ∘ ∘ 22 12 4 ∘ ∘ 23 12  6 x x 24 12  8 x x 25 12 10 x x 26 12 12 x x 27 12 14 x x

[0230] The above results show that favorable element formation is notachieved when the traveling velocity of the carriage in the X-directionbecomes greater than one third (⅓) the ejection velocity.

[0231] Upon comparative study of the results in table 5 and table 6, thefollowing can be said: Specifically, when a drop-on-demand inkjet headusing piezo elements is employed to eject a solution droplet, thecarriage traveling velocity can be increased, as compared with thethermal inkjet head, because the droplet becomes spherical according tothe principle of liquid ejection, as illustrated in FIG. 16. Even if thedroplet becomes elongated in the direction flight, as illustrated inFIG. 17, the length of the elongated droplet is controlled so as not toexceed three times the diameter thereof, without causing minute dropletsor particles behind the droplet. Even if the carriage traveling velocityis set faster in the piezo-element drop-on-demand inkjet head than inthe thermal inkjet head, a functional device can be formedappropriately, which exhibits satisfactory device performance. Inaddition, such piezo-element drop-on-demand inkjet head is beneficial inits simple structure, in which the displacement of the piezo element ismechanically propagated to the liquid directly or via the oscillationplate (thereby ejecting a droplet using a force produced by themechanical displacement). Since no thermal force acts on the liquid,unlike in the case of the thermal inkjet head, a wide variety of liquidscan be selected to form a functional device.

[0232] In other words, various different types of functional devices canbe formed using a drop-on-demand inkjet head using piezo elements, aslong as the ejection velocity is set greater than the carriage travelingvelocity.

[0233] Moreover, the shape of the droplet can be easily controlled so asto be spherical, or even if the droplet is elongated in the direction offlight, the length of the droplet can be controlled so as to be withinthree times the diameter, without causing undesirable liquid-particlestrailing behind the ejected droplet. Accordingly, a good functionaldevice mounting board can be obtained without undesirable minutedroplets spreading on the substrate.

[0234] Of course, a thermal inkjet method may be used to form thefunctional device. In this case, a good functional device mounting boardcan be obtained if the carriage traveling velocity is set equal to orsmaller than one third (⅓) the ejection velocity. If the carriagetraveling velocity suitable for the piezo-element drop-on-demand inkjethead is selected for the thermal inkjet head, it becomes difficult toform a satisfactory functional device mounting board. By selectingappropriate heat-resistant fluids, desirable functional device formationis also achieved even using a thermal inkjet head.

[0235] Although the testing results are not specifically mentioned here,a continuous flow method can be equally used, which is capable ofcreating a uniform droplet as shown in FIG. 16. In this case, thecarriage can be driven under the same conditions as in the piezo-elementdrop-on-demand inkjet head. Accordingly, the carriage traveling velocityis set smaller than the ejection velocity of the fluid droplet.

[0236] An electrostatic type drop-on-demand inkjet head may also beused, which uses accumulation and discharge of electrostatic forcebetween two opposed electrodes as the displacement principle, instead ofthe physical displacement of the piezo element. The accumulation anddischarge of electrostatic force causes a mechanical displacement of theoscillation plate, which then creates a droplet similar to that createdby the piezo element. In this case, the conditions are selected so thatthe carriage traveling velocity is slower than the ejection velocity.

[0237] Next, another feature of the present invention will be described.As described earlier, with the present invention, functional devices areformed using an inkjet technique to eject a droplet containing afunctional material onto a substrate (e.g., a glass substrate or aceramics-based substrate). The dot shape formed by the application ofthe fluid droplet between device electrodes becomes important. If afavorable round dot is formed on the substrate, highly precise formationof the functional device can be achieved. However, when the dot shape isdegraded, the functional device cannot be formed precisely. Forinstance, if the dot formed on the substrate is not round, but withdispersed minute droplets, a good functional device cannot be obtained.

[0238] Generally, inkjet printers eject ink droplets onto paper toreproduce an image, and the dots of the ink droplets attached to thepaper are quickly absorbed into the fibers of the paper when the inkdroplet hits the paper. If paper is coated with an ink absorbentmaterial, such as calcium carbonate, the ink droplet is immediatelyabsorbed into the coating film of the ink absorber when the ink dropletreaches the paper. Accordingly, even if a subsequent droplet hits thesame position as the previous droplet, no ink dispersion occurs becausethe previous droplets has already been absorbed into the paper, withoutcausing problems. Consequently, a favorable round dot is obtained, andhigh-resolution print quality can be obtained.

[0239] Meanwhile, the present invention involves the inkjet technique toeject a droplet onto a substrate (such as a glass substrate, aceramics-based substrate, or a plastic-based substrate) that does notabsorb the droplet, but maintains it on its surface. Accordingly, unlikethe ejection of ink droplets onto paper, the droplet remains on thesubstrate with a slightly flattened semi-spherical shape. The volatileingredients of the fluid droplet vaporize, while other ingredientsremain on the substrate. If the subsequent droplet hits the previousdroplet before the solidification of the ingredients, dispersion orsplattering of the minute droplets occurs, which disturbs the desiredformation of functional devices. This also applies to the first dropletbecause the droplet is not absorbed in the substrate, unlike the case inwhich the ink droplet ejected from a inkjet printer is immediatelyabsorbed in the fiber of paper. The first droplet may also disperseunless the optimum conditions are chosen. This is a major differencebetween the present invention and an ordinary inkjet printer designedfor printing on paper.

[0240] In other words, because a fluid droplet is ejected onto asubstrate (e.g., a glass substrate, a ceramics-based substrate such asalumina, or a plastic-based substrate) having a surface property thatholds the fluid without absorbing it, the conditions have to be chosencarefully so as to create a round dot on the substrate, while preventingdispersion of the droplet; otherwise, a good functional device mountingboard cannot be produced. Taking this point into consideration, theappropriate conditions for forming a favorable round dot withoutdispersion upon formation of the dot were found through experiment. Theexperiment results are shown in table 7.

[0241] The test involved ejection of droplets of a solution containing afunctional material onto a silica glass substrate with a mirror-polishedsurface based on the inkjet principle, the impacting fluid containingfunctional material. The ejection velocity of the droplets was varied,and the dot conditions (including the positioning accuracy and the shapeof the dot formed on the substrate) were observed. Dispersion of liquidparticles (minute droplets) about the major dot was also examined. Then,aluminum was sputtered to form a functional device in order to checkwhether the functional devices correctly worked as an organic EL deviceemitting a prescribed degree of light.

[0242] The specific conditions for this experiment are given below.

[0243] The solution used was a 0.2 wt. % solution of polyhexyloxiphenylene vinylene mixed with O-dichlorobenzene/dodecylbenzene mixedsolution.

[0244] The jet head used in the experiment had a construction similar tothe edge-shooter type thermal inkjet head (see FIG. 22). Instead of arectangular nozzle, a nozzle plate with round nozzle openings in the endface of the fluid channel was attached to this jet head. Instead of ink,the above-mentioned solution was used. The nozzle diameter was 25 μm,and the size of the heating element was 25 μm×90 μm (with a resistancevalue of 118 Ω) The driving voltage was selected ranging from 20 V to 24V, and the pulse width was 5 μs to 7 μs. The ejection velocity of thedroplet was varied within the range of 0.5 m/s to 12 m/s to examine thepositioning accuracy of droplet on the substrate, as well as the dotshape and dispersion of minute droplets. The experiment results areshown in table 7. The carriage scanning speed was set to 0.1 m/s inorder to remove the instability factor when ejecting droplets. (Thecarriage traveling velocity was made slower than the ejection velocityof fluid droplets so that the carriage motion would not degrade thepositioning accuracy of the droplets on the substrate).

[0245] In Table 7, a circle marked in the droplet positioning accuracydenotes the case in which dot offset was within half the dot diameter,and a cross mark denotes the case in which the dot offset was greaterthan half the dot diameter. In the cross-marked cases (test Nos. 1through 3), the dot offset was varied ranging from one dot diameter tofive dot diameters. As for the dot shape, a circle represents afavorable round dot. A triangle represents a slightly deformed round dotestimated through sensory evaluation although, in general, almost around shape was obtained. Concerning dispersion of liquid particles (orminute droplets), a circle indicates the case in which no dispersion wasobserved, and a cross mark indicated the case in which dispersion ofminute droplets (tiny splatters around the major dot) was observed.

[0246] Lead lines of ITO and aluminum were extended to make the ITOanode and make the aluminum cathode, and a voltage of 12 volts wasapplied to check the device performance by examining whether or notfavorable orange light was emitted. A circle represents the case inwhich a predetermined shape of orange light was emitted, and a crossmark denotes the case in which orange light was not emitted or onlypartially emitted (unsuitable for actual use). TABLE 7 Minute EjectionDroplet droplet Test velocity positioning Dot dispersion Device No.(m/s) accuracy shape status performance 1 0.5 x Δ ◯ x 2 1 x Δ ◯ x 3 2 x◯ ◯ x 4 3 — ◯ ◯ ◯ 5 4 — ◯ ◯ ◯ 6 5 — ◯ ◯ ◯ 7 6 — ◯ ◯ ◯ 8 7 — ◯ ◯ ◯ 9 8 —◯ ◯ ◯ 10 9 — ◯ ◯ ◯ 11 10 — ◯ ◯ ◯ 12 11 — Δ x x 13 12 — Δ x x

[0247] The experiment result indicates that it is necessary to set theejection velocity of fluid droplet to the range between 3 m/s to 10 m/sin order to form a good functional device (an organic EL device mountingboard, in this case), in view of the positioning accuracy, the dotshape, and the condition of dispersion of minute droplets. In otherwords, by setting the ejection velocity of the fluid droplet within theabove-mentioned range, the ejection becomes stable and the positioningaccuracy is improved. In addition, since the droplet reaches thesubstrate at an appropriate speed, undesirable mist or dispersion of thedroplet can be prevented even if a subsequent droplet hits the previousdroplet on the substrate. Consequently, a precise pattern of functionaldevices can be formed without variation in device performance amongfunctional devices.

[0248] Next, another arrangement of the present invention will bedescribed. In FIG. 4, a droplet 43 is ejected onto the space between apair of device electrodes 42, and the functional device is illustratedas a round dot image 44 placed between the electrodes. If a functionaldevice to be formed requires a not so high degree of precision, alarge-sized droplet 43 is placed between the electrodes 42, therebyforming the functional device as a dot image 45, as shown in FIG. 19.For instance, if the distance between the device electrodes 42 is 5 mmto 10 mm, and if the dot diameter is 8 mm to 15 mm, then the functionaldevice can be formed by a single dot application. In this case, only acertain degree of precision can be expected for the functional device;however, as long as ordinary functionality is achieved, application of asingle droplet for forming a device is very efficient. The ordinaryfunctionality is, for instance, light emission if the device is alight-emitting device, switching if the device is a transistor, orelectron discharge if the device is an electron discharge device.

[0249] Nevertheless, in order to form a more precise functional device,it is desired to form the device with multiple droplets that defines adot pattern 45 having a smoother outline, as illustrated in FIG. 20. Ina preferred example, it is assumed that the distance between the deviceelectrodes 42 is set to 140 μm. In this case, if a functional device isformed with a single droplet, the dot diameter is about 180 μm. If thesame device is formed with four dots, as in FIG. 20, the dot diameter isabout 65 μm. In the latter case, four dot patterns make an alignmentbetween the electrodes 42, overlapping each other to fill the 140 μmgap. Whether to form the functional device with a single droplet ormultiple droplets can be determined appropriately, depending on theintended productivity and precision. The preferred conditions chosen tocreate the four-droplet dot pattern shown in FIG. 20 are describedbelow.

[0250] The solution used to form the functional device was 0.2 weightpercent polyhexyl oxiphenylene vinylene mixed in6-dichlorobenzene/dodecylbenzene mixed solution.

[0251] The jet head has a structure similar to that used in the edgeshooter type thermal inkjet technique (but using the above-describedsolution, instead of ink). To create a dot with a diameter of about 65μm, as shown in FIG. 20, the nozzle diameter of the jet head was 28 μm,and the size of the heating element was 28 μm×90 μm having a resistancevalue of 121 Ω. The driving voltage was 24.6 V, the pulse width was 6μs, and a driving frequency is 10 kHz. The energy for producing adroplet was approximately 30 μJ, and the ejection speed was about 7 m/s.

[0252] These conditions were specifically chosen to generate four dotsbetween the device electrodes 42 separated by a distance of 140 μm, andtherefore, the present invention is not limited to these conditions.FIG. 21 illustrates another example, in which two lines of droplets,each consisting of five droplets, are placed between the same deviceelectrodes 42 separating by 140 μm. In this example, the dot diameter is45 μm. To create this size of dot image, the nozzle diameter of the jethead is 20 μm, and the size of the heating element is 20 μm×60 μm with aresistance value of 102 Ω. The driving voltage is 13.5 V, the pulsewidth is 4 μs, and the driving frequency is 16 kHz. The energy forproducing a droplet is approximately 7.1 μJ. The ejection velocity ofdroplet is 6 m/s.

[0253] Of course, the length between the device electrodes 42 is notlimited to 140 μm. If the functional device mounting board is used for ahigh resolution image display apparatus, the functional devices have tobe arrayed more densely. In such a case, the distance between the deviceelectrodes 42 may be set to 50 μm. The jet head may have nozzles with adiameter of 20 μm and a corresponding size of heating elements. Thedriving conditions are also appropriately selected in accordance withthe degree of precision. In the present invention, the number ofdroplets applied between the device electrodes may be suitably chosenfrom 1 through 30 droplets, and suitable conditions are chosen inaccordance with the distance between the device electrodes 42 and theprecision requirement. The number of droplets applied between theelectrodes also depends on the nozzle diameter of the jet head, but fromthe standpoint of productivity, it is preferable that the number be atmost 30 droplets. (While it is possible to apply a greater number ofsmaller droplets, productivity decreases and it becomes disadvantageousfrom the standpoint of cost.)

[0254] Next, overlap of the droplets when the functional device isformed by multiple droplets placed between the device electrodes will bedescribed. In the previous example, the length between the deviceelectrodes 42 is 140 μm. If this distance is filled by a single dropletas in FIG. 19, the dot diameter is approximately 180 μm. The 140 ,,m gapbetween the device electrodes 42 can be filled with ten droplets eachwith a diameter of 45 μm to create a highly precise pattern, asillustrated in FIG. 21. In FIG. 21, each dot is drawn as a circle lineto indicate the outline and how the dots overlap each other.

[0255] In the example shown in FIG. 21, the droplets are ejected so thatdiagonally adjacent dots are tangent to each other. In other words, thetwo lines of dots are arranged so that distance 1x between the centersof two horizontally adjacent dots, and distance 1y between the centersof two vertically adjacent dots each becomes ½^(1/2) (1/{squareroot}{square root over ( )}2) times the dot diameter. This condition isthe marginal condition necessary to cover the entire underlayer withdots when filling the gap between the electrodes with multiple droplets.Accordingly, in the present invention, the dots are arranged so that thelengths 1x and 1y in two perpendicular directions between the centers oftwo dots aligning in the two perpendicular directions become 1/{squareroot}{square root over ( )}2 times the dot diameter or smaller, for thepurpose of completely covering the underlayer.

[0256] By ejecting the droplet so as to satisfy the above-describedcondition, the solution containing the functional material completelycovers the under layer located between the device electrode, and thequality of each functional device becomes stable. In addition, since aplurality of dots of droplets hit the substrate overlapping each other,the dot pattern becomes smoother, and consequently, a highly precisefunctional device can be formed.

[0257] The specific conditions for forming this sort of fluid dropletand dot are shown below.

[0258] The solution used was 0.2 weight percent solution of polyhexyloxiphenylene vinylene mixed in o-dichlorobenzene/dodecyl benzene mixedsolution.

[0259] The jet head has a structure similar to that used in the edgeshooter thermal inkjet method (but using the above-described solution,instead of ink). The nozzle diameter of the jet head was 20 μm, whichwas used to create the dot with a diameter of 45 μm as shown in FIG. 21.The size of the heating element was 20 Mm×60 μm with a resistance valueof 102 Ω. The driving voltage is 13.5 V and the pulse width was 4 ,,s.The energy required to produce a droplet was approximately 7.1 μJ. Theejection velocity was approximately 6 m/s.

[0260] These conditions were chosen to fill the gap of 140 μm betweenthe device electrodes with ten droplets, and the invention is notlimited to this example. The number of drops is not limited to ten, andmore droplets may be used. Similarly, the invention is not limited tothe arrangement of two lines of five dots shown in FIG. 21, and three ormore lines of dots may be formed.

[0261] Again, the length between the device electrodes 42 is not limitedto 140 μm. If the functional device mounting board is used for a highresolution image display apparatus, the functional devices have to bearrayed more densely. In such a case, the distance between the deviceelectrodes 42 may be set to 50 μm. The jet head may have nozzles with adiameter of 20 μm and a corresponding size of heating elements. Thedriving conditions are also appropriately selected in accordance withthe degree of precision.

[0262] The number of droplets applied between the device electrodes maybe suitably chosen from 2 through 30 droplets, and suitable conditionsare chosen in accordance with the distance between the device electrodes42 and the precision requirement, without being limited to fixedconditions. In short, it is important to place the dots so that thelengths 1x and 1y between the centers of two horizontally and verticallyadjacent dots becomes 1/{square root}{square root over ( )}2 times thedot diameter, in order to completely cover the underlayer locatedbetween the device electrodes with the dots.

[0263] Next, the jet head according to the present invention will bedescribed in conjunction with FIG. 22. In this example, the jet head hasfour nozzles. This jet head is formed by coupling a thermal elementsubstrate 51 and a cover substrate 52. The thermal element substrate 51has individual electrodes 54, a common electrode 55, and heatingelements (energy creating members) 56, which are formed on a siliconsubstrate 53 by a wafer process.

[0264] Meanwhile, the cover substrate 52 has grooves 57, which becomechannels for guiding the solution containing a functional material, anda recess 58 that configures a common fluid chamber (not shown in thefigure) for reserving the solution, which is to be guided through thechannels. The cover substrate 52 is combined with the thermal elementsubstrate 51 as shown in FIG. 22A, whereby the channels and the commonfluid chamber described above are created.

[0265] When the thermal element substrate 51 and the cover substrate 52are coupled to each other, the thermal elements 56 are positioned in thebottom of the channels. In this state, nozzles 50 are formed at the endsof the channels to eject a portion of the solution guided through thesechannels as fluid droplets. In addition, a solution inlet port 59 isformed in the cover substrate 52 to allow supply of solution into thesolution supply chamber using supply means (not show in the figure).

[0266]FIG. 22B is a perspective view when the thermal element substrate51 and the cover substrate 52 are separated, and FIG. 22C is a bottomview of the cover substrate 52 shown in FIG. 22B.

[0267] In the example shown in FIG. 22, the ends of the trenches 57become the nozzles 50 with no additional configuration; however, it isalso allowable for nozzle plates in which round nozzles have been openedto be provided at these ends. In this example, a four-nozzle jet head isshown. This type of multi-nozzle jet head is capable of forming afunctional device efficiently. Of course, it is not always necessary tohave four nozzles. It is naturally understood that a greater number ofnozzles will allow functional elements to be formed more efficiently.Nevertheless, this does not mean that the number of nozzles is simplyincreased. As the number of nozzles increases, the cost of the jet headincreases and clogging is more likely to occur in the jet nozzles.Accordingly, the above-described factors should be determined, takinginto account the overall balance of the apparatus (including the balanceof the cost and the fabrication efficiency).

[0268] The same applies to the length of the nozzle array (the effectivejet width of the jet heads). Namely, merely increasing the length of thenozzle array (the effective jet width of the jet heads) is inadequate,and the overall balance of the apparatus (balance of apparatus cost andfunctional device fabrication efficiency) has to be considered.

[0269] To give an example, with the present invention, the number ofnozzles and the array density thereof are determined so that the lengthof the multi-nozzle nozzle array (the effective jet width of the jetheads) is equal to or greater than the length between the deviceelectrodes 42. However, it is not intended here for the term “greater”to mean infinitely greater, but rather slightly greater than the lengthbetween the device electrodes 42. Therefore, the basic idea of thepresent invention is that by using a jet head with a nozzle array length(effective jet head jet width) equal to the length between the deviceelectrodes 42, the cost of the jet head can be minimized. This idea alsorealizes efficient fabrication of functional devices.

[0270] To give more specific values, a pattern made of four droplets isformed between the device electrodes 42 with a distance of 140 μmbetween them. In this case, the length of the four-nozzle array shown inFIG. 22 (which is the effective jet width of the jet heads or the lengthbetween the nozzles on each end) is approximately 127 μm This length canbe regarded as substantially the same as the length of 140 μm betweenthe device electrodes 42. The distance between adjacent nozzles isapproximately 42.3 μm. When viewed in terms of inkjet printers, thisarrangement would correspond to a nozzle array density corresponding to600 dpi (dots per inch).

[0271] The above-described example is directed to the four-nozzle jethead shown in FIG. 22; however, a six-nozzle jet head with aninter-nozzle length of 42.3 μm can also be used. In this case, with thepresent invention, the length of the six-nozzle nozzle array (theeffective jet width of the jet heads or length between the nozzles oneach end) is approximately 212 μm, which can be interpreted as largerthan the length of 140 μm between the device electrodes 42. The distancebetween the device electrodes 42 can be sufficiently covered by thelength of the nozzle array, which allows functional devices to befabricated efficiently.

[0272]FIG. 23 shows a view of the multi-nozzle fluid jet head fabricatedas described above when seen from the nozzle 50. In the presentinvention, such a multi-nozzle jet head is provided for each type ofsolution to be ejected, and a plurality of multi-nozzle jet heads areloaded on the carriage, as illustrated in FIG. 24. FIG. 25 is aperspective view of FIG. 24.

[0273] In FIG. 24 and FIG. 25, each of the multi-nozzle fluid jet headsare assigned reference symbols A, B, C, and D. The nozzles of each ofthe jet heads A, B, C, and D are arranged apart from the nozzles ofother jet heads, and these jet heads are filled with solutionscontaining different kinds of functional materials. For example, eachjet head is filled with a solution containing a different organic ELmaterial for emitting light of red, green, or blue, and ejects thesolution to predetermined positions.

[0274]FIG. 24 and FIG. 25 show an example of multi-nozzle fluid jetheads integrated into a single head unit according to the invention.There may be a structure as shown in FIG. 26 as an integrated head unit,which has a common nozzle plate 60 with a number of nozzles 61 formedtherein. However, this head unit has a problem. If different solutionsfilled in the adjacent jet heads flow along the common nozzle plate, andif the mixture of these different solutions is ejected from the nozzles,then the resultant functional device cannot exhibit the intendedfunction. This may degrade the quality of the functional devices.

[0275] The example shown in FIG. 26 is an inkjet printer head. In thecase of inkjet printing, even if different inks mix with each other on asingle, common nozzle plate surface, and even if such mixed ink isejected onto paper, the problem is not so serious, although the imagequality may be slightly degraded. This is because, in the case ofinkjet, the image reproduced on the paper is not a functional device,and it does not have to exhibit a specific function, unlike the presentinvention. Therefore, it is difficult to apply the integrated head unitwith a single, common nozzle plate shown in FIG. 26 and used in aninkjet printer head to the present invention. Although the presentinvention employs the multi-nozzle jet head unit to eject differenttypes of solutions containing different functional materials from therespective jet heads, the ultimate object to be formed is a functionaldevice, such as an organic EL device or an organic transistor. Such afunctional device has to exhibit the intended function. If undesirableimpurities are mixed in the functional device, the device performancenaturally drops, and becomes unsuitable for practical use.

[0276] In consideration of the above-described points, the presentinvention uses a fluid jet head unit as shown in FIGS. 24 and 25, inwhich the nozzle part of each jet head is separate from other jet heads.In other words, with the present invention, each fluid jet head isindependently formed, and thereafter assembled into a single unit. Sincethe nozzle part of each jet head is independent of other jet heads, asolution will not become mixed into other solutions of other jet heads(unlike the structure shown in FIG. 26 having a single, common nozzleplate, where a solution is very likely to flow to the neighbor jet headsand become mixed to the other solutions).

[0277] To implement the above-described concept more effectively, thefluid jet heads may be combined into a unit with each jet headcompletely separate from each other, as illustrate in FIG. 27.

[0278]FIG. 28 illustrates another arrangement of the present invention,showing the relation between the carriage moving direction and thepositioning of the multi-nozzle jet head unit. The multi-nozzle jet headunit is loaded on the carriage. The carriage is driven in the scanningdirection, while the multi-nozzle jet head unit ejects droplets ofsolution containing functional materials.

[0279]FIG. 28A is an example where the direction of the multi-nozzlearray of each jet head is set perpendicular to the carriage movingdirection. FIG. 28B is an example where the array direction of themulti-nozzle jet head is inclined with respect to the carriage movingdirection, with a certain angle from the vertical.

[0280]FIG. 29 and FIG. 30 show comparison examples in which thedirection of the nozzle array is parallel to the carriage movingdirection, unlike the present invention. The arrangement shown in FIG.29 is disadvantageous because the multi-nozzle jet head unit cannot bemade compact. The arrangements shown in both FIG. 29 and FIG. 30 aredisadvantageous because jet efficiency is poor. (In the case of FIG. 29and FIG. 30, a single type of solution must be shot by four nozzles, andin addition, the carriage has to be driven for each group of nozzles.)

[0281] According to the present invention, as shown in FIG. 28, thedirection of the multi-nozzle array of the jet head is inclined so as tobe non-parallel to the carriage moving direction when the carriagescans, while allowing ejection of droplets from the multi-nozzle jethead unit. Accordingly, the problems in the structures shown in FIG. 29and FIG. 30 can be resolved, realizing a compact jet head unit. For thecontinuous scanning motion of the carriage, a single jet head thatejects a single type of solution is appropriately driven as necessary,without requiring the above-described group control.

[0282] The configuration shown in FIG. 28B also has an advantagethat-the shot density becomes higher than the nozzle density of thearray. This arrangement is especially advantageous if the jet headcannot have a high-density nozzle arrangement (for example, if a jethead utilizes piezoelectric elements as shown in FIG. 41 and FIG. 42,which will be described later).

[0283] Next, another feature of the present invention is described usingFIG. 31. As previously described in conjunction with FIG. 2 and FIG. 3,the jet head ejects droplets onto a substrate so as to form a group offunctional devices, while performing relative displacement with respectto the substrate (the functional device mounting board) 14. FIG. 31illustrates the device electrodes 42 formed on the substrate (functionaldevice mounting board) 14, a functional device group formed by applyingfour droplets in between those device electrodes 42 along the verticaldirection (slow-scanning direction) (see enlarged view of FIG. 31B), anda view of the jet head from the nozzle surface (see FIG. 31C). Thelateral direction is defined here as the fast-scanning direction.

[0284] For simplification of description, described here is an exampleof a case where the relative displacement between the jet head andsubstrate (functional device mounting board) 14 is placed in front ofthe substrate (functional device mounting board) 14 as in the case ofFIG. 2, and the jet head mounted on the carriage applies droplets whilemoving in the main-scanning direction and sub-scanning direction.

[0285] As described above, FIG. 31 shows a group of functional devices,each being formed by applying four droplets between device electrodes 42along the longitudinal direction (slow-scanning direction). In thepresent invention, not only a group of an array of functional devices,but also another pattern is formed on the substrate 14 using the jethead during the fabrication of a functional device mounting board. InFIG. 31, the ranges X and Y extending in the fast scanning direction andthe slow scanning direction, respectively, define a functional deviceforming area on the substrate 14. There are additional spaces outside ofthe functional device forming area, which are indicated by ranges Xa,Xb, Ya, and Yb. The fabrication apparatus is designed so as to allow thecarriage to scan over the peripheral areas defined by Xa, Xb, Ya, andYb. Accordingly, the jet head mounted on the carriage can apply dropletsto these peripheral areas as the carriage moves in the fast scanningdirection and the slow scanning direction. The substrate: (functionaldevice mounting board) 14 has a functional device forming area, and aperipheral area located around the functional device forming area.

[0286] By setting certain dimensions of peripheral area on the substrate14, and by designing the fabrication apparatus so as to allow thecarriage or the jet head to be movable in the peripheral area on thesubstrate, a pattern other than the functional device array can beformed on the substrate 14. In the example shown in FIG. 31, thesubstrate 14 has a pattern of figures “123”, which cab be a productnumber. A manufacturing date or a serial number can also be formed onevery substrate using the jet head. The pattern formed in the peripheralarea is not limited to figures, but any symbols or characters can beformed to identify the substrate.

[0287] Generally, a serial number or other identification mark isaffixed to or imprinted on a finished product. With the presentinvention, such a number or a mark can be formed directly on thesubstrate during the formation of the functional devices. Thisarrangement is advantageous when fabricating a product or a unit (suchas a functional device mounting board) that requires high precision anda clean environment. Affixing a plate to the substrate or imprinting amark in the substrate may cause contamination, which further causes theintrinsic functionality and performance to be degraded. With the presentinvention, the marks or patterns are formed on the substratesimultaneously with forming an array of functional devices in the cleanenvironment (usually, in a clean room of approximately class 100 to1000). Consequently, a precise functional device mounting board can beproduced without causing a problem of contamination. Furthermore, sinceno additional apparatus for conducting the subsequent imprinting processis required, the production efficiency is improved, and the manufacturecosts can be reduced.

[0288]FIG. 32 illustrates another example of the functional devicemounting board, which has four extra functional devices formed in theperipheral area defined by the ranges Xa, Xb, Ya, and Yb, near thecorners of the substrate 14. Similar to the example in FIG. 31, thearray of functional devices is formed in the functional device formingarea defined by the ranges X and Y. Each functional device is formed offour droplets of solution applied to the space between the deviceelectrodes 42 in the vertical direction (slow scanning direction). Eachof the four extra functional devices is also formed of four dropletsduring the inkjet process.

[0289] Each of the four extra functional devices has the same electrodesand the same thin film of functional pattern as those used in the actualfunctional device formed in the functional device forming area. Theseextra functional devices are provided for the purpose of conducting aperformance test. Because checking all the functional devices in thearray takes time and increases the cost, test patterns are provided nearthe corners of the substrate, outside the functional device formingarea. With this arrangement, the performance of the functional devicearray can be checked in a short time, without examining all the devices.As the checking method, if organic EL devices are examined, an ITO leadand an aluminum lead are extended out from the check pattern (ordevice). A voltage is applied between the ITO as the anode and thealuminum as the cathode to check whether or not light is emitted (todetermine pass or fail).

[0290] Although, in the example, a test pattern that is the same as theactual functional device is used, a simplified check pattern may be usedfor the performance test. The number of test patterns is not limited tofour. However, forming test patterns at the four corners is preferablerather than forming test patterns at one place when a large-sizedsubstrate is used to fabricate a functional device mounting board. Ifthe substrate is smaller than 200 mm×200 mm, test patterns could beformed at one place on the substrate. However, if the substrate used tofabricate a functional device mounting board has a size larger than theabove-mentioned dimensions, it is preferable to arrange test patterns atseveral different locations on the substrate in order to guarantee auniform quality of the device over the wide area of the substrate. Thisis because the purpose of providing test patterns is to check whether anumber of functional devices arranged over a wide area of the substratehave been formed uniformly irrespective of the location.

[0291] As has been described, the functional device mounting board ismanufactured by ejecting droplets of a solution containing a functionalmaterial onto a substrate so as to fill the space between each pair ofdevice electrodes. The substrate is larger than the functional deviceforming area, and therefore, other patterns can be formed in the areaoutside the functional device forming area by ejecting droplets. To thisend, the fabrication apparatus is configured so that the carriage or thejet head is movable to the area beyond the functional device formingarea.

[0292]FIG. 33 illustrates yet another example of the functional devicemounting board having a functional device forming area and a peripheralarea outside the functional device forming area. In this example, asecond group of functional devices is formed in the peripheral areadefined by the range Ya. The second group of functional devices isformed by ejecting droplets of a solution containing a functionalmaterial onto the substrate in the same manner as the formation of thefirst group of functional devices.

[0293] For example, the first group of organic EL devices and the secondgroup of organic EL devices are formed on the same substrate tofabricate a functional device mounting board. By placing a transparentcover plate made of glass or plastic so as to face the functional devicemounting board. The transparent cover plate and the functional devicemounting board can be packaged into a unit to produce an image displayapparatus, such as spontaneous light-emission type organic EL display.In this case, signals are input to the second group of functionaldevices to drive each device, and images are displayed in the secondarray, in addition to the first array.

[0294] By changing the signal information supplied to the second groupof organic EL devices for each product, the product serial number andother information can be displayed on the final product. By changingcolor information supplied to the second group of organic EL array foreach lot, a certain set of image displays can be easily distinguishedfrom other product sets, using the-color information as the identifierof the lot. This arrangement can also eliminate the necessity of astamping or imprinting process, which is conducted using a separateapparatus after the fabrication of the product.

[0295] In the description above, the second group of functional devices(organic EL devices) is provided separate from the first group offunctional devices (organic EL devices). However, the extra information,such as color ID information or product numbers, can be displayedwithout forming a separate group of functional devices (organic ELdevices). For example, by switching signals between the imageinformation and the extra information when supplying them to thefunctional device array, a color ID or a product number can be displayedon the array of functional devices. Alternatively, the color ID or theproduct number may be displayed in a portion of the functional devicearray, together with the image information, without switching thesignals.

[0296] Since the droplet ejection area of the fabrication apparatus isset larger than the functional device forming area of the substrate, atest pattern or an ID pattern can be formed on the substrate, inaddition to the array of functional devices. The peripheral area outsidethe functional device forming area can also be used to conduct a testshot of the jet head prior to actually forming a functional device. Thisarrangement is advantageous to guarantee the stable performance of thefabrication apparatus, as well as the reliable characteristics of thefunctional device mounting board.

[0297]FIG. 34 illustrates another arrangement of the present invention,showing a schematic structure of the fabrication apparatus. This drawingis used to explain the apparatus shown in FIG. 2 in more detail. In FIG.34, reference numeral 11 denotes a jet head unit (jet head), 12 denotesa carriage, 13 denotes a substrate support bench, 14 denotes a substrateforming a functional device, 15 denotes a supply tube for the solutionthat includes functional material, 70 denotes an auxiliary container, 71denotes a fluid container, 72 denotes a container holding member, 73denotes the rim of the container holding member, and 74 denotes a pump.

[0298] As clearly shown in FIG. 34, the fluid container 71 for thesolution that includes functional material in the present invention isdeployed lower than the substrate 14, which forms the functional devicethat is mounted onto the substrate support bench 13. In this manner, ifby chance the solution overflows or leaks from the fluid container 71,accidents where the functional device group formation surface of thesubstrate 14 is contaminated by leaking solution are eliminated sincethe fluid container 71 is deployed lower than the substrate 14.Furthermore, that fluid container 71 is placed and held on top of thecontainer holding member 72. Accordingly, likewise in this case, even ifthe solution leaks due to an unexpected accident, the leaked solutionfirst remains upon the container holding member 72 without immediatelyflowing to the floor and contaminating the floor, or wetting nearbyelectrical systems, thus not inducing serious accidents.

[0299] However, in cases where a large amount of solution flow out, itmay flow out from the container holding member when that containerholding member is simply upon a flat plane. Taking such points intoconsideration, the present invention has the container holding member 72having the rim 73 that surrounds the outside of the fluid container 71,and makes the height of that rim 73 to be higher than (greater than) themaximum level (fluid level 78) of the solution in the fluid container 71(see FIG. 37). With this type of configuration, the solution will neverexceed the rim 73 and flow out.

[0300] Furthermore, as another configuration, making the containerholding member 72 have the rim that surrounds the outside of the fluidcontainer 71, and making the height of the rim 73 be a height such thatthe capacity of the container holding member 72, which is determined bythe height of that rim 73, is greater than the fluid volume of the fluidcontainer 71. With this type of configuration, even if the solution inthe fluid container 71 leaks due to an unexpected accident, the leakedsolution can be retained and prevented from flowing elsewhere, thuspreventing serious accidents. As two configuration examples have beendescribed thus far, with this kind of configuration, even if by chancethe entire solution within the fluid container 71 leaks due to anunexpected accident, the container holding member 72 is capable ofpreventing the solution from flowing elsewhere, thereby damage of theelectrical system of the fabrication apparatus of the present inventionmay be eliminated.

[0301] Next, another feature of the present invention is described. Withthe present invention, as described above, the fluid container 71 forthe solution that includes functional material is deployed lower thanthe substrate 14, which forms the functional devices that are placed onthe substrate support bench 13. That solution must then be supplied upto the jet head 11 that is positioned higher than the substrate supportbench 13 or the substrate 14, which forms the functional devices placedthereupon. In the case where the amount of solution used is little orthe frequency of being jet as droplets is low (for example, several tenHz to several hundred Hz per nozzle), supplying the solution naturallywithin the solution supply tube 15 based on principles of the capillaryphenomenon is sufficient. However, in the case where the jet head 11that includes multiple nozzles (several ten to several hundred) is usedand the frequency of jetting the solution as droplets is high (forexample, several kHz to several ten kHz per nozzle), the solution needsto be supplied by some kind of action rather than naturally. Inparticular, in case of the present invention, since the fluid container71 is deployed lower than the substrate 14, which forms the functionaldevices that are placed upon the substrate support bench 13, and evenfor compensating for the head difference, supplying fluid by some kindof forcible action is necessary.

[0302] With the present invention, as shown in FIG. 34, the pump 74 ismade to intervene the jet head 11 and the fluid container 71.Accordingly, even though the aforementioned head difference exists or alarge amount of solution is utilized at a high frequency (even if thejet head 11 is operated at a high drive frequency), an empty jet ofdroplets due to deficient capability of supplying the solution occurs,thereby preventing failure in functional device formation.

[0303] It should be noted that with the present invention, this pump 74is also deployed lower than the substrate 14, which forms the functionaldevices that are placed upon the substrate support bench 13.Accordingly, similar to the solution leakage of the above fluidcontainer 71, assuming the case where a solution leakage has occurred inthe pump 74 due to an unexpected accident, accidents where thefunctional device group formation surface of the substrate 14 iscontaminated by leaked solution are eliminated.

[0304] Furthermore, though not shown in FIG. 34, the pump 74 of thepresent invention is also placed and held on top of a pump holdingmember (not shown in the drawing) such as the container holding member72 that holds the fluid container 71, so as to prevent leaked solutionto flow out elsewhere.

[0305] Next, with such type of pump 74, the solution that includesfunctional material is transported from the auxiliary container 70 tothe jet head 11 via the solution supply tube 15. Here, the jet head 11is mounted on the carriage 12 and carriage return movement is performedin a position opposing the substrate 14, which forms the functionaldevices. Thus, flexible material is selected for the solution supplytube 15. For example, a polyethylene tube, polypropylene tube, or Teflon(registered trademark) tube is preferably utilized. Furthermore,depending on the used solution that includes functional material, a tubethat cuts off light may be required. For example, in the case of usingphotosensitive resin or photo-curing adhesive, a supply tube 15 thatcuts off light of wavelengths at which that material is exposed shouldbe used.

[0306] The solution that is to be supplied to the jet head first entersthe auxiliary container 70 before being transported to the jet head 11.Though the auxiliary container 70 has a role of temporarily retaining asolution 76, the solution 76 is not retained to the full capacity of theauxiliary container 70 but is retained in a form such that a layer ofair 77 exists as shown in FIG. 34. Namely, since the solution suppliedvia the pump 74 has the pulsation of the pump 74, it is first entersinto the auxiliary container 70 where the pulsation is eliminated usingthe layer of air 77 as a buffering means, and is then supplied to thejet head 11 through a capillary phenomenon. Through execution of suchsolution supply, droplet jet performance of the jet head 11 stabilizes,allowing for formation of a favorable functional device group.

[0307]FIG. 35 through FIG. 37 are diagrams illustrating a furtherspecific example of the fluid container 71 and container holding member72, which are conceptually shown in FIG. 34. FIG. 35 illustrates thefluid container 71 implemented as a cartridge in a pre-utilized state.It should be noted that in FIG. 35, reference numeral 75 denotes an aircommunicating hole, 76 denotes the solution, 78 denotes the fluid level,79 denotes a fluid-flow inlet and 80 denotes a closing object. Suchfluid container 71 that is implemented as a cartridge is, for example,set before utilization in an air tight state by the tape-like closingobject 80, which is capable of maintaining adherence and airtightness.Immediately before utilization, the tape-like closing object 80 is thenremoved so as to release the air tight state (FIG. 36), and is pusheddown towards (direction indicated by the arrow Y in FIG. 36) thecontainer holding member 72. A fluid-flow entry needle 82,which iscapable of pouring fluid into syringe needle-like interior portions, isutilized by inserting into the fluid-flow inlet 79, which is formed withan elastic member of rubber or the like (FIG. 37).

[0308] A container holding material 81 of FIG. 36 is a member forholding the fluid container 71, which is implemented as a cartridge, andis made of an elastic member of rubber or the like. This then not onlyexternally supports the fluid container 71 but also functions as asealing element such as an O-ring, which is capable of sealing even incases where the solution leaks from the fluid-flow inlet 79 due tounexpected accidents.

[0309] Though the aforementioned description is an example of the fluidcontainer 71 with a cartridge structure, being implemented as acartridge enables to easily replenish the solution (solutionreplenishment through cartridge exchange) without soiling the user'shands. It should be noted that the fluid container 71 implemented as acartridge of the present invention does not contain the solution 76 forthe entire capacity of the container, as is shown by the fluid level 78in FIG. 35 and FIG. 36. Furthermore, the height of the top of the regionwherein the air passage hole 75 is formed is made to be higher than theother regions. These are means for preventing the users from dirtyingtheir hands with the solution that overflows from the air passage hole75 when preparing the container for use by peeling off the closingobject 80 and inserting the fluid-flow entry needle 82 into thefluid-flow inlet 79, as shown in FIG. 36 and FIG. 37. The fluid level 78in FIG. 37 is lower than the fluid level 78 in FIG. 35 or FIG. 36because the solution moves to the side of the fluid-flow entry needle 82and supply tube 15 linking therebetween when preparing the container foruse by inserting the fluid-flow entry needle 82 into the fluid-flowinlet 79.

[0310] Furthermore, as described above, the-fluid level 78 is set to belower than the height of the rim 73, which is provided so as to surroundthe outside of the fluid container 71 on the container holding member72, so as to prevent the solution 76 from leaking to the outside due toan unexpected accident, thus preventing accidents with electricalcomponents in the device as well as contamination of the surroundings.

[0311] Next, another feature of the present invention is described. FIG.38 illustrates a modified example of the fabrication apparatus of thepresent invention shown in FIG. 34, and in the drawing, referencenumeral 77 denotes a layer of air, 76 denotes a solution, 83 denotes afilter a, and 84 denotes a filter b.

[0312] As described above, with the present invention, the pump 74 ismade to intervene the jet head 11 and the fluid container 71.Furthermore, with such pump 74, the solution that includes functionalmaterial passes through a fluid supply route 85 and the solution supplytube 15, to be transported from the auxiliary container 70 to the jethead 11, however a filter 83 and a filter 84 are made to intervenetherebetween. The jet head 11 is mounted upon the carriage 12, andcarriage return movement is performed in a position opposing thesubstrate 14, which forms the functional devices. Thus, flexiblematerial is selected for the solution supply tube 15. For example, apolyethylene tube, a polypropylene tube, or a Teflon (registeredtrademark) tube is preferably utilized.

[0313]FIG. 39 is a system diagram (pump 74 and auxiliary container 70are omitted) illustrating the solution flow of the present invention.With the present invention, at least two types of filters (filter 83 andfilter 84) are provided further downstream than the fluid container 71.This is for preventing the solution from clogging in the nozzles sincethe solution is jet from a minute nozzle based upon inkjet principleswith the present invention.

[0314] Here, the filter 83 is the main filter for the jet system of thepresent invention, and it is a membrane filter with a 0.45 μm pore size(or filter mesh size), which can remove or trap foreign particles of0.45 μm or greater. The filter material is cellulose nitrate, celluloseacetate, polycarbonate, Teflon (registered trademark), or the like, andis accordingly selected in consideration of compatibility with thesolution that includes functional material to be used. It should benoted that a membrane filter with an even smaller pore size (e.g., 0.2μm) can be equally used; however, when pore size is too small, thefilter is quickly clogged and solution flow worsens, whereby the filtermust be frequently exchanged. Accordingly, the pore size should bedetermined in consideration of the exchange frequency. However, a filterof pore size 2 μm or greater is ineffective as a filter function in thejet system of the present invention, thus the pore size must not exceedthereof.

[0315] Though the present invention suitably uses a 0.45 μm membranefilter, in the jet system of the present invention, almost all foreignparticles in the solution that flows from the fluid container 71 to thejet head 11 are trapped here. Accordingly, the filter trap capacity(trap capacity for foreign particles) of this filter 83 is madesignificantly greater than that of the filter 84 at bottom stream.

[0316]FIG. 40 is another example of a system diagram illustrating thesolution flow of the present invention. This example also has at leasttwo types of filters (filter 83 and filter 84) provided furtherdownstream than the fluid container 71, however, here an example isgiven where the filter 84 is embedded in the jet head 11.

[0317] An example of a jet unit configured by the jet head 11 and filter84 with the aforementioned structure is illustrated in FIG. 41 and FIG.42 along with the principle for jetting solution droplets. This fluidjet head 11 is one provided with piezoelectric devices 91 as an energyaction unit within a flow route 90 wherein the solution 76 isintroduced. If a pulse signal voltage is applied to the piezoelectricdevices 91 to warp the piezoelectric devices 91 as shown in FIG. 41(A),the capacity of the flow route 90 reduces as well as a pressure waveoccurs, whereby that pressure wave causes a droplet 43 to be ejected outof the nozzle 1. FIG. 41(B) illustrates a state where the piezoelectricdevices 91 are no longer warped and the capacity of the flow route 90 isincreased.

[0318] Here, the solution 76 that is introduced into the flow route 90adjacent to the nozzle 1 has passed through the filter 84. As describedthus far, with the present invention, the filter 84 is provided withinthe jet head to realize a filter removing function at the nearestpossible location to the nozzle 1. Foreign particles are removed by theaforementioned main filter (filter 83) with nearly 100% accuracy,however foreign particles that are mixed in during main filter (filter83) exchange cannot be removed by the main filter (filter 83). Thereforethe filter 84 is provided nearest to the nozzle 1 in this manner.Accordingly, this filter 84 is made un-detachable since it is providednearest to the nozzle 1 (since foreign particles will repeatedly mix induring that operation if filter exchange is performed).

[0319] However, the main filter (filter 83) predominantly removesforeign particles in the jet system of the present invention, howeverthis filter 84 is strictly a supplementary means. Accordingly, in orderto ensure removal of foreign particles as described above, the filtertrap capacity of the main filter (filter 83) must be significantlygreater than that of the filter 84, and the pore size (filter mesh size)must be less than that of the filter 84. Namely, making the filter 84 bea compact and simple filter with a small filter trap capacity and a poresize (filter mesh size) greater than that of the filter 83 enables it tobe embedded in the jet head 11 as shown in FIG. 42. The jet head 11 canthen be made compact.

[0320] Furthermore, as shown in FIG. 39, even in the case where thefilter 84 is provided external to the jet head 11, similar to the abovedescription, using a compact and simple filter enables it to be mountedupon the carriage 12 shown in FIG. 38 and realize a compact carriage. Astainless-steel mesh filter is preferably used for such filter 84, andthe pore size thereof (filter mesh size) should be 2 μm to 3 μm. Sincethis filter 84 is strictly a supplementary compact and simple filter,selecting a small filter mesh size as described above causes the filterto immediately be clogged (since the filter trap capacity is small sinceit is compact enough to be embedded in the jet head 11) and thus cannotbe used. Therefore, the filter mesh size should be greater than that ofthe filter 83.

[0321] An important point of the present invention is for at least twotypes of filters to be provided downstream from the fluid container.Among these, the filter provided at bottom stream is fixed andun-detachable, and a plurality of filters may also be provided upstream.

[0322] Furthermore, another important point is that the filter providedat bottom stream is provided within the jet head, and has a filter meshsize greater than that of the filter provided further upstream.Moreover, the filter provided at bottom stream is provided within thejet head and has a filter trap capacity less than that of the filterprovided further upstream. As long as these qualities (filter mesh sizeand filter trap capacity) are satisfied, a plurality of filters may beprovided on the upstream side of the filter that is provided at bottomstream.

[0323] Next, another feature of the present invention is described. InFIG. 43, reference numeral 95 denotes maintenance equipment formaintaining reliable operation of the fabrication apparatus. Referencenumeral 12 denotes a carriage, and numeral 11 denotes a jet head. Thejet head 11 is placed and held on top of the carriage 12, and ejectsdroplets onto the substrate to form a desired pattern. Furthermore, themaintenance equipment 95 is installed in a region other than the regionwherein the functional device mounting board is set, and is verticallymoved along the direction indicated by the arrow Y in the drawing forcapping and suctioning the solution ejecting surface of the jet head 11(non-capped state is shown in the drawing).

[0324]FIG. 43 is a typical diagram illustrating the positional relationof the maintenance equipment 95 of the present invention, and FIGS.44(A) and 44(B) are used for describing the functions and structure ofsuch maintenance equipment 95 for suctioning and discharging thesolution and capping the solution ejecting surface.

[0325] In FIG. 44 and FIG. 45, reference numeral 101 denotes a jet headmounted upon a carriage 102, and reference numeral 103 denotes a nozzleattached to the tip of the jet head 101. A chamfered portion 102 a isprovided on the left-and-right external walls (upper and lower externalwalls in FIG. 44(A)) of the carriage 102 near the jet head 101. A recess101 a is made by notching the tip of the jet head 101. Reference numeral104 denotes a cap slide and 105 denotes a power lever that presses theslide 104 towards the carriage 102. In the cap slide 104, a deep hole107 filled with a solution absorbing body 106 is opened at a cap portionthat is opposite to the jet head 101. A path 106 a is provided at thecenter of the solution absorbing body 106.

[0326] At the tip of the cap portion, a recess 108 to which thechamfered portion 102 a can fit therewith is formed opposite thecarriage 102. At the center of the4 recess 108 is implanted an elasticcap 109 formed to cover the solution absorbing body 106 and fit togetherwith the recess 101 a on the jet head 101 through pressure welding. Ahole 109 a linking to the path 106 a is opened at the center of thiselastic cap 109.

[0327] On the other hand, in the cap slide 104, a shaft hole 110 isopened parallel to the deep hole 107, and a shaft 111 is inserted intothis shaft hole 110 as shown in FIG. 44B. The shaft 111 is fixed with asnap ring 113 or the like to a cap fastening plate 112, which isattached to the main unit of the device. At the other end of the shaft111, a boss 114 is joined and fitted inside the shaft hole 110 byinsertion, and at the other end portion of the shaft 111 is fixed to thetip portion of the boss 114 by a snap ring 115.

[0328] Accordingly, when the cap slide 104 is moved towards the het head101, the shaft hole 110 is capable of sliding along the boss 114 in thedirection of the shaft line. A compressed trigger 116 is then mountedbetween the shaft hole 110 and boss 114 so that the cap slide 104 isslanted towards the fastening plate 112 during such sliding motions.Reference numeral 117 denotes a springy locking member for locking thepower lever 105 when it turns counterclockwise. Reference-numeral 140denotes a suction pump main unit of a nozzle suction device, and 135denotes a suction tube that links the path 106 a to the suction pumpmain unit 140. Still referencing to FIG. 45, details of the suction pumpmain unit 140 and suction tube 135 are described.

[0329]FIG. 45 illustrates an example of a nozzle suction device providedto the maintenance equipment 95 of the present invention, where 140denotes the cylindrical-shaped main unit of the suction pump fixed to abase 121. The suction pump main unit 140 includes a suction chamber 122of a large diameter, and a ring-shaped sealing groove 123 that is formedat the top end portion on the other side of the suction chamber 122. Inthe suction pump main unit 140, an aperture 120 a is opened above thissealing groove 123. An O-ring 124 is fit into this sealing groove 123.In the suction pump main unit 140, a shaft 125 that is fixed to the base121 is extended upwards to reach the vicinity of the tip of the sealinggroove 123. Reference numeral 141 denotes a piston of the suction pump,and this piston 141 includes a small-diameter portion 128 of a shapethat allows for inserting into the aperture 120 a and the sealing groove123 and then sliding, and its top end portion is fixed to theaforementioned lever 105.

[0330] The lower end portion of the piston 141 includes a large-diameterportion 127 to fit together with the suction chamber 122, and a path 129that runs through the large-diameter portion 127 in the axis directionis opened at a rim portion of this large-diameter portion 127 protrudingfrom the small-diameter portion 128. At the lower end side of this path129 on the side of the suction chamber 122 is mounted a valve 130 thatopens and shuts in accordance with variances in differential pressure atboth end aperture portions of the path 129. Furthermore, an c-ring 131is mounted on the external walls of the large-diameter portion 127 so asto perform sealing between such external walls and the suction chamber122. Furthermore, a recess 132 is notched at the suction chamber sidebottom surface of the large-diameter portion 127 of the piston 141, anda compressed trigger 133 is attached between this recess 132 and thebase 121. This compressed trigger 133 is used for the piston 141 toautomatically return upwards after the piston 141 is manually pusheddownward as needed.

[0331] A communicating hole 134 is opened at the upper sidewall of thesuction chamber 122, and a suction tube 135 is connected to thiscommunicating hole 134. The other end of the suction tube 135 is linkedto the path 106 a of the solution absorbing body 106 as shown in FIG.44(B). Accordingly, relative to a dead air space 136 in anegative-pressure state that is formed between the large-diameterportion 127 of the piston 141 and the upper end portion of the suctionpump main unit 140 when the piston 141 is pushed downwards, the path 106a is suctioned into a negative pressure state from the communicatinghole 134 via the suction tube 135. Furthermore, opened on a sidewall (onthe left sidewall in FIG. 45) at the lower portion of the suction pumpmain unit 140 is a hole 137 to let out the negative pressure in the deadair space 136 when that dead air space 136 is extended downwards andfurthermore, is able to discharge solution.

[0332] Next, operation of the head maintenance equipment 95 configuredas described thus far is described with reference to FIGS. 46(A) and (B)and FIG. 47. FIGS. 46(A) and (B) illustrate a state where the lever 105is locked with the locking member 117 by electrically turning the lever105 counterclockwise (direction indicated by the arrow in FIG. 44(A)),and the elastic cap 109 at the tip of the cap slide 104 is welded withpressure to the jet head 101, and its nozzle 103 is tightly sealed.Together with that, the nozzle 103 is inserted in the hole 109 a so thatit faces the solution absorbing body 106 behind the cap 109.

[0333] In a case where sucking in and discharging the solution, as shownin FIG. 47, negative pressure is generated in the dead air space 136 bypushing the piston 141 downwards, and that negative pressure is used fordrawing the tip of the nozzle 103 and ejecting the solution outwardsfrom the nozzle 103. To realize this, first as shown in FIGS. 46(A) and(B), the elastic cap 109 at the tip of the cap slide 104 is welded withpressure to the jet head 103, and in that state the lever 105 is pusheddownwards as if being slid between a cap fastening plate 112 and capslide 104 so as to push down the piston 141. At this time, since thedead air space 136 formed between the large-diameter portion 127 of thepiston 141 and the upper end portion of the suction pump main unit 140becomes negative pressure due to cubical expansion caused by the piston141 being pushed downwards, the interior of the path 106 a also becomesnegative pressure. Furthermore, because the tank (not shown in thedrawing) that supplies solution to the jet head 101 is a constantair-releasing type, the solution in the nozzle 103 is ejected outwardsfrom the nozzle 103 by the differential pressure at the front and backof the nozzle 103.

[0334] Next, if the piston 141 is released, the compressed trigger 133makes the piston 141 return upwards as shown by the arrow in FIG. 47. Atthis time, since the valve 130 is configured of a film with a thicknessof several 10 μm, it acts sensitively in accordance with variances inthe differential pressure at the top and bottom, and the valve 130 isopened so that the solution, which is sucked into the dead air space136, is discharged to the outside from the hole 137 that is providedbelow the suction pump main unit 140. It should be noted that making theline resistance of the path 129 smaller than the line resistance of thesuction tube 135 enables the solution collected in the dead air space136 to be easily discharged from the path 129.

[0335] The side wall 102 a of the tip of the carriage 102 is chamfered,a recess 108 is formed at the cap slide 104 that comes in contactherewith, and a projection is formed at the elastic cap 109, as has beendescribed above. Accordingly, even if some displacement occurs betweenthe carriage 102 and the cap slide 104, such displacement in thepositional relation between them is absorbed and corrected by the recessand the projection. Consequently, the jet head 101 is tightly sealed bythe cap slide 104 in a reliable manner.

[0336] As described thus far, with the present invention, themaintenance equipment 95 is installed outside of the region where thefunctional device mounting board is set. This is because providing themaintenance equipment 95 between the jet head 11 and functional devicemounting board 14 with the present invention is extremely difficultsince a functional device group is formed by the jet head unit (jethead) 11 jetting solution while performing carriage displacement in theX direction (or Y direction or both X and Y directions) in parallel tothe functional device mounting board 14 while maintaining a fixeddistance (for example, 0.1 mm to 10 mm) in relation to the functionaldevice mounting board 14.

[0337] It is not impossible to insert a thin-plate cap in the narrowrange of 0.1 mm to 10 mm, which is the distance between the jet nozzlesurface and the functional device mounting board 14, if only to allowthe maintenance equipment 95 to simply function as a cap for the jetnozzle surface of the jet head. However, even in this case,high-precision techniques for inserting a thin-plate cap are required,where a single misstep would hurt the jet nozzle surface and damage it,thus impairing the function of the fabrication apparatus formanufacturing functional device mounting boards.

[0338] Though it is possible to assume that the maintenance equipment 95is beneath the functional device mounting board 14, in other words, thatit is configured to be embedded in the substrate support bench 13, thefunctional device mounting board 14 must be removed or moved whenevercapping or suction is performed, and is extremely inefficient.Furthermore, there is a risk of damaging the functional device mountingboard 14.

[0339] The reason for installing the maintenance equipment 95 in aregion other than the setting region for the functional device mountingboard is derived from consideration of this point. By installing themaintenance equipment 95 in a region other than the region where thefunctional device mounting board is set, the jet head is well maintainedwithout clogging and guarantees stable operation-without degrading thefunctions of the fabrication apparatus, or without reducing themanufacturing efficiency.

[0340] Next, another example of the present invention is described usingFIG. 48. In this example, the maintenance equipment 95 operates in theregion where the functional device mounting board is placed, in otherwords, in the region where droplets are ejected for forming functionaldevices. The carriage is designed so that the jet head 11 is pivotableabout the rotational shaft 96. When the maintenance equipment 95 isattached to the jet head, the jet head 11 is turned away (rotated 90degrees to the right in the drawing) from the droplet ejectingdirection, as illustrated in FIG. 48A.

[0341] With this type of structure, the device can be configured withouteven installing the maintenance equipment 95 in a region other than theregion where the functional device mounting board is set, thus allowingfor reduction in projected floor space of the fabrication apparatus ofthe present invention and size.

[0342] Incidentally, as for the amount of solution sucked by themaintenance equipment 95 in the fabrication apparatus of the presentinvention, with the present invention, the amount of solution suctionedis equivalent to at least the internal volume of the jet head andchannels in the regions further downstream than the filter 84 shown inFIG. 40 and FIG. 41, namely the filter provided at bottom stream. InFIG. 42, the solution of at least the internal volume from downstreamfrom the filter 84 to the nozzle 1 is to be suctioned. This is because,with the present invention, the filter 84 is deployed at bottom streamto trap foreign particles thereat such as described. Therefore, as longas the solution in the head fluid chamber therebeyond is suctioned bythe maintenance equipment 95, clogging may be avoided.

[0343] As described thus far, with the present invention, since theminimum required amount of the solution to be suctioned for maintainingreliability has been clarified, low-cost and speedy stable operationwithout jet head clogging is possible without unnecessarily sucking ordiscarding large amounts of solution.

[0344] It should be noted that though the above description was for anexample that includes two filters, filter 83 and filter 84, the presentinvention is not one to be necessarily limited to two filters. Inaddition to these two filters, a third and fourth filter may beprovided.

[0345] Next, another feature of the present invention is described.According to the present invention, as described thus far, for forming afunctional device group, droplets of a solution are jet to jet throughthe air so as to adhere to a substrate. At that time, the problem is theyield for manufacturing such type of functional device or thatfunctional device mounting board. As described above, the functionaldevice mounting board of the present invention is formed based on theinkjet principle, thus is preferably applied to the manufacture ofrelatively large (200 mm×200 mm to 4000 mm×4000 mm) functional devicemounting boards. At that time, the problem is a defective device(namely, the reduction in yield for device manufacture) generated byforeign particles that are floating in the air, such as dust, adheringto the portion where a functional device is formed. Such problem withdust also applies to the LSI manufacturing field, where countermeasuresof its own kind are taken. However, in the present invention, thesubstrate size is larger compared to the Si wafer (6 to 8 inches) usedin the LSI manufacturing field, thus exponentially increasing theprobability of dust to be adhered from, whereby the rate of a defectivedevice occurring is enormously high.

[0346] Furthermore, with the present invention, since the jet headmounted upon the carriage constantly plies utilizing the inkjetprinciple, an adverse environment where floating dust constantly flutteris self-created. This point is also a problem of technique unique to thepresent invention, and is one of the large reasons for reduced yield.

[0347]FIG. 49 is a diagram for describing an embodiment of the presentinvention. In one aspect of the present invention, a system forfabricating a functional device mounting board is provided. Such asystem comprises a fabrication apparatus 157 for fabricating afunctional device mounting boar by ejecting and applying droplets of asolution that contains a functional material onto the substrate, and aclean air supply unit for supplying clean air to the fabricationapparatus. The fabrication apparatus 157 may be placed in a room, abuilding, a booth, or any other housing. In FIG. 49, reference numeral151 denotes a ceiling, 152 denotes an outside wall, 153 denotes aninternal ceiling, 154 denotes an inside wall, 155 denotes a floor, and156 denotes a column of the floor 155. FIG. 49 does not show thedetailed configuration of the building, but shows only showing the majorparts of it.

[0348] In FIG. 49, a HEPA filter 158 (High Efficiency Particulate AirFilter) is installed on the ceiling, and substantially cleaned air thathas passed through the HEPA filter flows downward from the ceiling intothe room. In addition to air passing down through a hole opened in thefloor 155, even if foreign particles such as dust generate or exist inthe room for some reason, they are then discharged beneath the floortogether with the cleaned air, thereby inside the room is continuallymaintained a cleaned environment. With the present invention, a systemis configured by arranging in such kind of room a fabrication apparatus157 for the functional device mounting board (shown as a rectangulardrawing in FIG. 49 to simplify the description) as illustrated in FIG.2.

[0349] Concerning the surrounding environment wherein such fabricationapparatus for the functional device mounting board is arranged, a roughstandard for cleanliness, for example, is class 100 (100 pieces or lessof dust with diameter 0.3 μm or greater per cubic foot) with the presentinvention. This is a million times cleaner than the environment of anormal room that is not regarded as such cleaned environment.

[0350] With the present invention, by intentionally creating suchenvironment and cleaning the entire surrounding environment, the regionwherein droplets are applied is made into a cleaned state and thenapplication of solution droplets is performed. Accordingly, with thepresent invention, as described above, though the device itself iscreating a less than favorable environment where dust is constantlyfloating in the air due to the repetitive carriage return movement,cleaning the environment to a greater degree allows for devicemanufacturing without dust coming near the region wherein droplets areapplied. This allows defect ratio due to dust for the functional devicemanufactured in the environment of the present invention to approach anegligible incidence.

[0351] It should be noted that an example where a fabrication apparatusfor the functional device mounting board as shown in FIG. 2 is arrangedin a room where an air cleaning system is operating has been explainedthus far. However, as another example, the air cleaning system may bemade to simply operate in such manner in only a certain area of the roomwithout cleaning its entirety. For example, in a case where only acertain area in a normal room is covered with an anti-dust curtain andHEPA filter is installed on the ceiling of that area, if a fabricationapparatus for the functional device mounting board as shown in FIG. 2 isarranged within that area, a similar cleanliness can be secured thoughthe frequency of exchanging filters increases. In this case, suchenvironment can be configured at a far lower cost than cleaning theentire room.

[0352] Furthermore, in the case where the size of the functional devicemounting board to be manufactured is small (200 mm×200 mm to 400 mm×400mm) and the fabrication apparatus such as that shown in FIG. 2 is alsocompact, a similar cleanliness can be secured even though thisfabrication apparatus is arranged within a large clean work station. Inthis case, such environment can also be configured at a far lower costthan cleaning the entire room.

[0353] Next, yet another example of the present invention is described.FIG. 50 is a diagram showing a jet head that is suitably used in thepresent invention, and a cleaned air applying head 162 is placed aroundthe jet head 161. It should be noted that for both the jet head 161 andcleaned air applying head 162, a fluid supply tube or gas supply tube orthe like that is to be connected thereto is omitted in the drawing. Thiscleaned air applying head 162 is integrated with the jet head 161 andmounted on the carriage, and the repetitive return movement is carriedout in the same manner as the jet head 161. In short, the region whereindroplets are applied by the jet head 161 is continuously cleaned by thecleaned air applying head 162. As the gas 163 to be used here, inaddition to air cleaned by a filter, for example, nitrogen gas cleanedby a filter may also be suitably used.

[0354] Incidentally, substantially cleaned air that flows via theaforementioned HEPA filter or gas that flows out from such cleaned airapplying head 162 is for cleaning the surface of the substrate 14 toform a favorable functional device, and is definitely not for blocking adroplet 43 from being adhered to the location for droplet application onthe substrate. To be specific, the stability of jettison for the droplet43 must not be adversely affected by the flow of this gas 163, lest theimpact precision of the droplet 43 to the location where a droplet isapplied be impaired.

[0355] For explaining this with the example of FIG. 50, upon contactwith the substrate 14, the cleaned air 163 (indicated by downwardarrows, and has a downward velocity vector component) is reflected, andflows upstream or forms a vortex (has a velocity vector component otherthan downwards). This must not disturb jettison (has a downward velocityvector component) of the droplet 43.

[0356] With the present invention, in consideration of this point, suchapparatus as shown in FIG. 49 is used to perform functional deviceformation by varying velocity of flow for the cleaned air 163 andvelocities for jetting the droplet 43 so as to examine the conditionsunder which the droplet favorably adheres to the functional devicemounting board to form a favorable functional device.

[0357] The substrate used is configured with the barrier wall 3 made ofpolyimide formed through photolithography on the glass substrate withITO transparent electrodes. On this substrate, using a fabricationapparatus utilizing the inkjet principle as shown in FIG. 2, a 0.1 wt. %solution polyhexyloxy phenylene vinylene of into a mixed solution ofo-dichlorobenzene/dodecyl benzene is applied based on the inkjetprinciple with the jet velocity changed. The distance between the jethead nozzle and substrate is assumed to be 3 mm.

[0358] The used inkjet head is a drop-on-demand inkjet head utilizingpiezo elements, in which the nozzle diameter is 23 μm, the voltage inputto the piezo elements is changed from 16 V to 28 V for changing the jetvelocity, and the drive frequency is 9.6 kHz. It should be noted that insuch kind of drop-on-demand inkjet head utilizing piezo elements, thejet velocity can be changed by changing the voltage input to the piezoelements. However, since the mass of droplets to be jet issimultaneously changed at this time, the mass of droplets to be jet ismade to be approximately constant (set at 5 pl) all the time throughcontrol of the drive waveforms (rising waveform and falling waveformincluding hit), thus only changing the jet velocity.

[0359] Furthermore, drop shape when a droplet is jetting is observedthrough a separate jettison under the same conditions as deviceformation, and the drive waveform is controlled such that that shape isnearly a round drop immediately before adhering to the substrate surface(3 mm in the present invention examples). It should be noted that evenif a perfectly round spherical shape is not achieved, but is columnarextended in the jetting direction, the drive waveform is controlled tokeep it under three times the length of that diameter. Furthermore, atthat time, drive conditions (drive wave form) that do not involve aplurality of minute droplets trailing behind the flying droplet ischosen.

[0360] Device formation is subsequently performed through deposition ofaluminum hereupon. The results given below are obtained when a 10Vvoltage is applied between the ITO anode and aluminum cathode, which areprepared by extending lead wires out from ITO and aluminum,respectively.

[0361] In this table, a circle marked for the status of device formationupon the substrate denotes that droplet impact has occurred in theintended region (within the barrier walls 3 enclosed with a polyimide),a triangle denotes that impact is partially outside of the intendedregion, and an “x” denotes that impact is completely outside of theintended region. A circle marked for device performance denotes that apredetermined shape of orange-colored light is emitted, and an “x”denotes that the orange-colored light is not emitted or only partiallyemitted (showing that device usage is not possible). TABLE 8 DeviceVelocity of Flow formation Jet cleaned air velocity status Test velocitystream Vc difference upon Device No. Vj (m/s) (m/s) Vj-Vc (m/s)substrate performance 1 2 0.5 1.5 Δ x 2 2 1 1 Δ x 3 2 2 0 x x 4 2 3 −1 xx 5 2 4 −2 x x 6 5 1 4 ◯ ◯ 7 5 3 2 ◯ ◯ 8 5 5 0 x x 9 5 7 −2 x x 10 7 2 5◯ ◯ 11 7 5 2 ◯ ◯ 12 7 7 0 x x 13 7 9 −2 x x 14 10 4 6 ◯ ◯ 15 10 6 4 ◯ ◯16 10 8 2 ◯ ◯ 17 10 10 0 x x 18 10 12 −2 x x

[0362] Accordingly, to the aforementioned results, a favorable devicecannot be formed on the substrate with a slow jet velocity such as 2m/s, and furthermore, favorable device performance can also not beobtained (usage of light-emitting qualities are also not possible). Onthe other hand, it can be known that in a case where the jet velocity isas fast as 5 m/s or more, though a favorable device can be formed on thesubstrate, a fast velocity of flow for the cleaned airflow may inhibitdevice formation. From the above results, it can be known that makingthe jet velocity of droplets to be at least 2 m/s greater than thevelocity of flow of the cleaned air flow enables favorable devices to beformed, and furthermore a favorable device performance to be obtained.

[0363] Next, another feature of the present invention is described.

[0364] As described above, the present invention is for manufacturingvarious functional device mounting boards through formation of afunctional device group by jetting and applying droplets of a solutionthat includes functional material onto a flexible substrate, such as aplastic substrate or a polymer film, and letting the volatileingredients contained in the solution vaporize such that solid contentsremain upon the substrate. At that time, the substrate 14 is installedon the substrate support bench 13 as shown in FIG. 2, which is installedin a flat state when forming a device by jetting solution. The statethereof after completion is shown in FIG. 51.

[0365] Such functional device mounting board is subsequently used as afunctional device such as a display or transistor or the like accordingto application thereof. Furthermore, in some cases it may bemanufactured largely and then cut into small sizes before utilization.Here, an example of manufacturing an organic EL display, for example, isdescribed.

[0366]FIG. 51 is a diagram for typically illustrating a displaysubstrate 170 upon which organic EL devices of the present invention areformed, and which is manufactured by an apparatus such as shown in FIG.2. This display is assumed to be viewed along the direction indicated bythe arrow in the drawing. To begin with, as shown in FIG. 51, an organicEL display substrate 170 is manufactured. It is then used in a curvedstate by utilizing the flexibility of the substrate so as to appearconvex when viewed in the direction as shown in FIG. 52, for example.Alternatively, it is used in a curved state so as to appear concave whenviewed in the direction as shown in FIG. 53.

[0367] Whether to make convex or concave is determined depending onapplication and actual use. For example, in the case where such organicEL display substrate of the present invention is used as an advertisingboard in a spacious area, it should be made convex as shown in FIG. 52in order to be seen wider angles.

[0368] Furthermore, in the case where such display is made large andused so as to be easily seen by people gathered in a specified area, itshould be made concave as shown in FIG. 53.

[0369] In either case, during manufacturing, the functional devicemounting board of the present invention is manufactured in a plain plateform, and is then curved in such manner for utilization.

[0370] At that time, to use a substrate that was originally in a plainplate form to begin with as a curved plate, a means to maintain thatsubstrate constantly curved is necessary. With the present invention,that status can be maintained by using, for example, a curve holdingguide provided as a holding means for holding the functional devicemounting board of the present invention.

[0371]FIG. 54 is a diagram for describing the aforementioned curveholding guide. FIG. 54(A) shows a state prior to where the organic ELdisplay substrate 170 is held in a guiding groove 181 of a guide member180, while FIG. 54(B) shows a state where the organic EL displaysubstrate 170 is inserted into the guiding groove 181. Furthermore, thisguiding groove 181 is bent in the vertical direction (direction alongthe depth) of the paper surface, and is able to achieve such curvedstates as shown in FIG. 52 or FIG. 53.

[0372] It should be noted that for simplification, only the lowerportion of the guide member is given in the example of FIG. 54, however,the curved state is actually maintained by installing such kind of guidemember to the lower and upper portions. Furthermore, these upper andlower guide members are linked with left and right holding members (notshown in the drawing) that provide support in the vertical direction soas to form a frame structure that surrounds and supports the contour ofthe organic EL display substrate of the present invention, and form suchcurved state.

[0373] As another possible method for forming a curved state, forexample, installing a support on the back surface of the organic ELdisplay substrate of the present invention, and then bending thatsupport so the organic EL display substrate copies thereafter may beconsidered.

[0374] An alternative method is to bend the wall and set the organic ELdisplay substrate 170 of the present invention thereat such that itcurves after that wall. Irrespective of structure, with the presentinvention, the flexibility of the substrate 170 allows that curved stateto be easily achieved.

[0375] Next, yet another feature of the present invention is described.As described thus far, by deploying a transparent cover plate made ofglass or plastic or the like opposite to the functional device mountingboard (for example, an organic EL display substrate) of the presentinvention and then casing (packaging) them, a self-luminous imagedisplay device may be achieved.

[0376]FIG. 55 is a diagram illustrating the aforementioned cover plate.FIG. 55(A) shows an example where a cover plate 190 is bent so as toappear convex when viewed from the direction (indicated by an arrow inthe drawing) that the display 170 (for example, an organic EL displaysubstrate) is viewed. By this means, unwanted light (sunlight,fluorescent light, unwanted reflected light slanting in from a window,and the like) and unwanted reflected images for the display that reflectagainst the cover plate surface can be reduced even if not removed sincethe cover plate surface is convex, thus realizing a more eye-friendlydisplay.

[0377] As described thus far, FIG. 55(B) shows an example where thecover plate 190 is bent in accordance with the display 170, which hasbeen bent utilizing the flexibility of the substrate of the presentinvention.

[0378] Such curved cover plate 190 is formed of glass or plastic or thelike, and manufactured by molding glass or plastic in a state that hasbeen curved with that curvature in advance.

[0379] Alternatively, similar to the functional device mounting board ofthe present invention, various plastic substrates including PET or apolymer-based film may be bent utilizing their flexibility.

[0380] In such case, such a state can be maintained by means of theaforementioned curve holding guide, which is used to bend and hold thefunctional device mounting board. Namely, there are two rows of guidinggrooves made of the guide member shown in FIG. 54, and should hold thefunctional device mounting board (display substrate) and cover plate.

[0381] It should be noted that two rows of guide groove are notnecessarily required, where a single guide groove may holdthe-functional device mounting board (display substrate) and cover platethrough close contact. A spacer may alternatively be interposed to makea little space therebetween.

[0382] Incidentally, the example where droplets are jet and applied tothe barrier wall 3 is illustrated in FIG. 1 at the beginning, however,such kind of barrier wall 3 shown in FIG. 1 is not necessarily requiredfor forming the functional device group of the present invention, andthe bottom line is that electrode patterns can be directly formed on theflat plate substrate, or functional devices can be formed by applyingdroplets. Furthermore, FIG. 4 shows a diagram where droplets are jetobliquely to the substrate surface. This diagram was illustrated to showdroplets jetting obliquely in this manner to show both the detectionoptical system 32 and jet head 33 in the drawing, however, droplets areactually jet and applied so as to hit the substrate almost vertically.

[0383] The description thus far is focused on the case where alight-emitting device is formed as the functional device, however, theformed light-emitting device substrate is subsequently utilized as adisplay device by deploying opposite to the transparent cover plate madeof glass or plastic or the like, and then casing (packaging) them.

[0384] Application is not limited only to the display apparatuses. Anorganic transistor or the like is suitably manufactured as a functionaldevice by utilizing the means of the present invention. Furthermore, afunctional device group can be manufactured on a large functional devicemounting board and then be subsequently made into small functionaldevice mounting boards or be cut into small chips before utilization.Moreover, the present invention can also be applied in the case where aresist pattern or resist material is used to form a three-dimensionalstructure by means of the use of resist material or the like as the jetsolution. In this case, a functional device of the present invention maybe a film pattern or even a three-dimensional structure formed with aresin material such as this kind of resist material.

[0385] Furthermore, a solution, in which minute metal particles (withdiameter of 0.001 μm to 1 μm) of Au or Ag or the like are dispersed inthe organic solvent, can also be used as a solution containing afunctional material. Such solution is preferably used for forming anaforementioned light-emitting device or an electrode pattern in anorganic transistor or the like.

[0386] The functional device mounting board fabrication apparatus ejectsand applies droplets of a solution containing a functional material ontoa substrate, and lets volatile ingredients of the solution vaporize,while allowing the solid contents remaining on the substrate to form afunctional device on the substrate. Since the droplet ejection area ofthe jet head can be set larger than the functional device forming areaof the substrate, another pattern can be formed outside the functionaldevice forming area, by ejecting and applying the droplets of solutiononto the area outside the functional device forming area.

[0387] With the fabrication apparatus for the functional device mountingboard that is used for an image display device, the region wherein thefunctional device group is formed is arranged at a fixed distance fromthe solution ejecting surface of the jet head, and since dropletapplication of a solution that includes functional material is performedby merely performing relative displacement of the functional devicemounting board and jet head in parallel to a functional device mountingboard surface, or in two mutually orthogonal directions, such functionaldevice mounting board can be manufactured with high-precision in asimple configuration.

[0388] The jet head ejects the solution making use of an acting forcecreated by mechanical displacement. The jet head produces a droplet sothat the droplet becomes almost spherical immediately before it reachesthe substrate. Alternatively, the droplet is controlled so that even ifit is elongated in the direction of the flying path, the length of thedroplet does not exceed three times the diameter, and no liquidparticles or minute droplets follow the flying droplet. Accordingly, ahigh-quality functional device and a high-quality functional devicemounting board can be obtained without undesirable adhesion of liquidparticles.

[0389] A jet head is mounted on a carriage that faces the substrate andis movable relative to the substrate. During the motion of the carriage,the distance between the droplet ejecting surface of the jet apertureand the top surface of the substrate is maintained constant. With thissimple configuration, the jet head ejects droplets onto the substrate toform a functional device mounting board.

[0390] The thickness of the substrate installed in a fabricationapparatus for a functional device mounting board is set to the rangebetween 2 mm and 15 mm. The substrate holder holds the substrate so asto be horizontal with a surface on which the droplets are appliedupward. Accordingly, a group of functional devices can be formedprecisely with a simple structure.

[0391] The substrate positioning/holding means is capable of angleadjustment. This arrangement also contributes to fabrication of a groupof functional devices formed on the substrate at high precision, and ahigh-quality functional device mounting board can be provided with asimple configuration.

[0392] The jet head is positioned above the substrate on which afunctional device is to be formed. The jet head is moved by carriagescanning with respect to the substrate with a constant distance betweenthe jet head and the substrate, while ejecting droplets downward to thesubstrate. The constant distance is set between 0.1 mm and 10 mm. Withthis arrangement, stable ejecting operation is realized with a simplestructure, and highly precise positioning of the droplet on thesubstrate is achieved.

[0393] The solution supplied to the jet head is retained in a containerprovided independently of the jet head, the container and jet head arelinked via a flexible supply path and the container is deployed lowerthan the substrate. Therefore, if by chance the solution leaks from suchcontainer, the solution does not contaminate the substrate or the regionwherein the substrate is held in the fabrication apparatus since thesolution flows only below the region wherein the substrate is set.Particularly, accidents of solution leakage occur only in the lowerportion so that damage to the fabrication apparatus can be kept to aminimum. Furthermore, even if such accident occurs during manufacturingthe substrate (during jetting), manufacturing of the substrate can becontinued and the problem handled later. Accordingly, the substrate isnot contaminated in the middle of manufacture nor is the processinterrupted so that a partially manufactured substrate is not wasted.

[0394] Solution is supplied to the fabrication apparatus simply byreplacing the empty container cartridge with a new one. The cartridge ischanged easily, without causing contamination interior or exterior ofthe fabrication apparatus.

[0395] A pump is arranged between the jet head and the container, and alarge quantity of solution is transported appropriately, preventingshortage of the solution. Ink is generally supplied based on principlesof the capillary phenomenon in an inkjet printer, without any particularmechanical force externally applied. However, with the industrialfabrication apparatus, such as that proposed by the present invention, alarge quantity of solution is consumed during the fabrication, andtherefore, solution supply based on the capillary phenomenon isinsufficient. If the solution is supplied based only on the capillaryphenomenon in the industrial fabrication apparatus, the drive frequency(frequency at which solution is ejected) of the jet head must bereduced. This results in decreased manufacturing efficiency. To overcomethis problem, a pump is employed to supply adequate quantity ofsolution, preventing the fabrication efficiency from falling. Even ifthe container is placed under the substrate (or under the jet head) forunexpected accident, adequate quantity of solution can be supplied bythe pump from the container located at a lower position.

[0396] The solution supplied to the jet head is retained in a containerprovided independently of the jet head, and the container and jet headare linked via a flexible supply path as well as at least two types offilters are provided further downstream than the container. Among thesefilters, the filter provided at bottom stream is made un-detachable soas to eliminate foreign particles flowing to the nozzle portion in thejet head that is further downstream than that filter and induceclogging.

[0397] The most downstream filter is provided within the jet head, andthe filter mesh size of the most downstream filter is greater than thatof the other filter(s) provided upstream. This arrangement prevents thesolution from clogging at the downstream filter, which is easy to beclogged, thereby guaranteeing stable operation.

[0398] The most-downstream filter is provided within the jet head, andhas a filter trap capacity smaller than that of the other filter(s)provided upstream. This arrangement allows the jet head unit to be madecompact because the most-downstream filter is small, while maintainingthe clog preventing function.

[0399] Maintenance equipment is provided outside the substrate settingarea. When the jet head is not used, the maintenance equipment caps thedroplet ejecting surface (in which nozzle apertures are formed), andevacuates the solution out of the jet head. This arrangement preventsthe jet head from clogging, and maintains the jet head in goodconditions, thereby guaranteeing stable operation, without impairing thefunctionality of the fabrication apparatus or the manufactureefficiency.

[0400] The angle or the orientation of the jet head is adjustable withrespect to the ejecting direction. When the jet head is not used, thejet head is pivoted or turned toward the maintenance equipment so as toface the maintenance equipment. This arrangement allows the fabricationapparatus to be made compact, while maintaining the jet head in goodcondition. Accordingly, clogging of solution in the jet head isprevented, and reliable and stable operation can be guaranteed.

[0401] A quantity of solution suctioned by the maintenance equipment isequivalent to at least the internal volume of the regions extendingfurther downstream the most-downstream filter. Consequently, stableoperation of the apparatus can be maintained without causing clogging inthe jet head, by the low-cost and short-time maintenance operation.

[0402] The ejection means (jet head unit) for ejecting a solutioncontaining a functional material onto the substrate can be comprised ofa plurality of multi-nozzle jet heads that ejects different types ofsolutions independently of each other. In the jet head unit, the nozzlesfor ejecting the respective solutions are arranged separately from eachother. The jet head unit is mounted on the carried so as to face thesubstrate. The direction of the nozzle array is non-parallel to thecarriage scanning direction when the jet head unit ejects droplets ontothe substrate during the carriage scanning. This arrangement realizes anovel and compact fabrication apparatus which is capable of fabricatinga high-performance functional device mounting board efficiently at a lowcost.

[0403] Since the jet velocity of the solution is set faster than therelative moving velocity between the jet head and the substrate, afunctional device mounting board having a precise pattern of functionaldevice array can be manufactured without deformation of the functionaldevices.

[0404] Since the jet velocity of the solution is set faster than thecarriage scanning velocity, a highly precise functional device mountingboard can be manufactured without deformation of the functional devices.

[0405] A single device can be formed by a plurality of droplets ejectedfrom the multi-nozzle type jet head in order to efficiently form a groupof precise pattern of functional devices.

[0406] Since the ejection velocity of the droplet ejected form the jethead is set within a prescribed range, stable ejecting operation isrealized and the positioning accuracy of droplet is improved. Moreover,since a droplet reaches the substrate overlapping the previous dropletat an appropriate velocity, undesirable droplet mist will not begenerated, without causing stains on the substrate. Thus, a pattern offunctional device can be formed precisely, without variation in deviceperformance among the devices.

[0407] In a manufacturing system using a fabrication apparatus forfabricating a functional device mounting board, droplets are ejected byan inkjet mounted on a carriage onto the substrate, while keeping thedroplet application space on and near the substrate clean with a simpleconfiguration.

[0408] In this manufacturing system, the fabrication apparatus is placedin a room in which an air cleaning system is operating in order to keepthe droplet application space clean. Therefore, even with a simpleconfiguration, defective devices due to adhesion of undesirableparticles or dust can be significantly reduced, and a high-qualityfunctional device array can be fabricated at high yield.

[0409] In this system, the ejection velocity of droplet is set fasterthan the velocity of the gas flow supplied from the air cleaning system.Consequently, a functional device mounting board can be fabricated athigh precision, without causing deformation.

[0410] A functional device mounting board has a matrix of functionaldevices formed by ejecting droplet of solution containing a functionalmaterial onto a substrate, and letting volatile ingredients vaporize,while allowing solid components to remain on the substrate. Thefunctional device mounting board has two mutually orthogonal sides. Thetwo mutually orthogonal directions of the functional device matrix areset parallel to the two mutually orthogonal sides of the substrate. Bysimply positioning the sides of the substrate, the positional offset (orshift) in the horizontal or vertical direction, as well as rotationaloffset, of the functional device forming the matrix can be eliminated.Consequently, a highly precise functional device mounting board can beobtained.

[0411] With the functional device mounting board, functional devices ofstrip patterns are arrayed in a matrix, so that the lines and columns ofthe strip-shaped functional device are parallel to the mutuallyorthogonal sides of the matrix. Accordingly, by simply positioning thestrip-shaped patterns, a matrix of functional devices can be formed onthe substrate without rotational offset of the angle component orpositional offset in the horizontal or vertical directions.Consequently, a highly precise functional device mounting board can beobtained.

[0412] By ejecting and applying solution droplets onto the area outsidethe functional device forming area of the substrates, a desired pattern,such as an identification pattern, a manufacture date, or amanufacturing number (product serial number), can be simultaneouslyformed during the formation of the functional devices. The resultantfunctional device mounting boards can be identified easily. A group offunctional device mounting boards can also be distinguishable for eachlot by forming a lot identification pattern on the substrate.

[0413] Particularly, forming a manufacture number or other patternssimultaneously with the formation of the functional devices is efficientbecause it does not require a separate imprinting process using specifictools or equipments, unlike the prior art techniques. This arrangementcan also eliminate the problem of contamination, which is caused in theprior art technique when a subsequent imprinting process is carried outusing specific equipment after the fabrication of the functional devicemounting board.

[0414] In the functional device mounting board, forming a plurality ofdevice electrode pairs on the outside of the functional device groupformation regions together with jetting and applying droplets of asolution that include functional material between those deviceelectrodes forms a pattern for checking the performance of thefunctional devices. This performance check can be performed after thefunctional device mounting board is manufactured, and since theperformance check can be performed for only this pattern portion withoutchecking the functional device groups, it is extremely efficient.Furthermore, for example, in a case where a light-emitting device isformed as the functional device, this pattern portion can be used forperforming a performance check for the functional device mounting boardbefore it is finally completed as an image display device and istherefore extremely efficient.

[0415] Since the solution that includes a plurality of functionalmaterial types is a solution wherein organic EL materials that emitdifferent colors are dissolved, a functional device mounting boardcapable of color light emission can be easily realized.

[0416] Since the surface roughness of the back surface is made rougherthan the surface forming the functional device group of the functionaldevice mounting board, a highly precise functional device group patterncan be formed, and substrate-manufacturing costs can be lowered.

[0417] Since the surface roughness of the surface forming the functionaldevice group is set to 0.5 s or less, a highly precise functional devicegroup pattern can formed and a high-performance functional devicemounting board can be obtained.

[0418] Since the problem during manufacturing where the substrate backsurface adheres to the fabrication apparatus during the manufacturingprocess of the functional device mounting board and thus cannot be movedmay be avoided by making the surface roughness of the back surface be 1s or greater, manufacturing yield is improved, and manufacturing costsare reduced.

[0419] Through providing linear forms on the back surface of the regionwhere the functional device group is formed of the functional devicemounting board so as to form a thin layer of air between the backsurface and the substrate supporting table of the functional devicemounting board fabrication apparatus, the situation has been avoidedwhere the substrate adheres to the substrate supporting table of thefunctional device mounting board fabrication apparatus whereby becomingimmobile while securing the substrate onto or removing it from thefunctional device mounting board fabrication apparatus during functionaldevice mounting board manufacturing. Accordingly, smooth substrateremoval as well as movement due to positioning, etc. becomes possible,and the manufacturing efficiency for the substrate can be significantlyimproved.

[0420] In particular, in the case where the substrate size is small (forinstance, approximately 100 mm×100 mm), even if such difficulties(problems relating to sticking and being hard to move) develop, itselimination can be easily accomplished without requiring a significantamount of energy. However, in the case of a large size substrate (300mm×300 mm or larger) to which the present invention can more effectivelyapplied, although it is difficult to eliminate adherence once fallinginto an adhered state, or while trying to eliminate adherence thesubstrate becomes damaged or other accidents occurr, by physicallyproviding a linear pattern on the back surface, and forming a thin layerof air between the back surface and the substrate support bench in thefunctional device mounting board manufacturing device, falling into anadhered state can be avoided, and it becomes possible to improvefunctional device mounting board manufacturing efficiency and eliminatedamage-related accidents.

[0421] Since the two (vertical and horizontal) chamfered ridgelineportions are also chamfered at the right angle-forming portion,accidents where workers are injured at only that right angle portionduring functional device mounting board manufacturing (during substratetransporting, exchanging, mounting onto the fabrication apparatus, andthe like) may also be eliminated.

[0422] Since the shape of the substrate is made rectangular and theshape of the angular portion of at least one of the four corners is madeto differ somewhat so as to be distinguishable from the other corners,the workers may identify substrate orientation during functional devicemounting board manufacturing, allowing for accurate performance ofsubstrate installation, improvement of substrate installation efficiencyand significant reduction in operational errors.

[0423] Since the shape of the substrate is made rectangular and a notchin at least one side of the four sides is provided, workers maydetermine substrate orientation when manufacturing the functional devicemounting board to make accurate substrate installation possible. Inaddition, not only is the worker able to verify substrate orientation,improve substrate installation efficiency, and significantly reduceoperational errors, but also accurate substrate installation onto thefabrication apparatus and accurate substrate positioning have been madepossible.

[0424] Since the ridgeline region that crosses with the front surface ofa substrate becomes the cover plate, and surfaces along the thicknessand perpendicular to that front surface are chamfered or the ridgelineregion that crosses with a back surface of a substrate becomes the coverplate, and the surfaces along the thickness and perpendicular to thatback surface are chamfered, accidents can be avoided such as workerscutting themselves during functional device mounting board manufacturing(during substrate transporting, exchanging, mounting onto thefabrication apparatus, and the like).

[0425] By implementing chamfering in the ridgeline portion, carelessaccidents by workers during functional device mounting boardmanufacturing can be prevented, and in addition, since the surfaceroughness of the chamfering portion is made rougher than the surfaceroughness of the surface of the region where the functional device groupis formed, but not formed with high precision surface roughness as withthe surface of the region where the functional device group is formed,low cost manufacture of the functional device mounting board becomespossible.

[0426] In other words, with the present invention, using a substratewhere the surface roughness of the back surface is made rougher than thesurface forming the functional device group of the substrate allows fora highly precise functional device group pattern to be formed, andsubstrate manufacturing costs can be reduced.

[0427] Since on the functional device mounting board, a single device ofthe functional device group is formed from a dot image with multipleliquid droplets applied on the substrate, dots neighboring in the twoperpendicular directions overlap, and each of the distances between thecenters of dots neighboring in the two perpendicular directions is equalto 1/{square root}{square root over ( )}2 (1/2^(1/2)) the dot diameteror less, the roughness level of the line pattern formed with a dot imageis low so that a high accuracy functional device pattern can be formed,and favorable functional device properties without variance amongdevices can be provided.

[0428] Further, since all these dots neighboring in the vertical,horizontal, and angle direction are in contact with each other oroverlap, there is no region where functional material is not applied inthe functional device portions, and therefore a functional devicemounting board with high precision functional devices are provided.

[0429] By using a flexible substrate, a flexible functional devicemounting board may be produced a low cost.

[0430] Making use of such flexibility of the substrate, the functionaldevice mounting board can be used in a curved state in actual use, whichallows a wide variety of use of the functional device mounting board.

[0431] When the functional device mounting board is used in a curvedstate, it is held by a curving guide provided to the holding means thatholds the functional device mounting board. The intended curved state ismaintained with a simple configuration and thus applied for varioususes.

[0432] Multiple species of solution containing different types oforganic EL materials that emit different colors are used in thefabrication apparatus to fabricate a functional device mounting boardhaving ability of color light emission.

[0433] Since highly precise functional device patterns can be formedwith less variation among the devices can be assembled into in an imagedisplay device, a high-resolution image display apparatus can beachieved.

[0434] The edge lines along the sides of the top surface of the coverplate used in an image display apparatus are chamfered. Accordingly,when attaching the cover plate onto the functional device mounting boardto assemble the image display apparatus, the workers are protected fromunexpected accidents, such as cutting themselves at the edges of theglass plate.

[0435] The edge lines along the side of the rear surface of the coverplate may also be chamfered. This arrangement can also protect workersfrom unexpected accidents.

[0436] The edges of the cover plate used in the image display device arechamfered. Accordingly, the workers are protected from unexpectedaccidents during the assembling process of image display apparatuses.Since the surface roughness of the chamfered portion is set greater thanthat of the top and rear surfaces of the substrate, without strictcontrol on the degree of roughness, the cost of the substrate can bekept low. Consequently, the manufacturing cost of the image displayapparatus can also be maintained low.

[0437] A highly precise functional device mounting board is covered witha cover plate. Since the cover plate is thicker than the functionaldevice mounting device, a high-resolution image display with amechanical strength can be provided.

[0438] Since reinforced glass is used for the cover plate of the imagedisplay, the display panel of the image display apparatus has mechanicalstrength so as to be hardly broken.

[0439] This patent application is based on and claims the benefit of theearlier filing dates of Japanese patent application No. 2002-068033filed Mar. 13, 2002 and Japanese patent application No. 2002-316419filed Oct. 30, 2002, the entire contents of which are herebyincorporated by reference.

What is claimed is:
 1. An apparatus for fabricating a functional devicemounting board, comprising: a holder for holding a substrate on which afunctional device is to be formed; a jet head for ejecting a dropletcontaining a functional material onto the substrate so as to form thefunctional device in a functional device forming area of the substrate,by allowing a volatile ingredient of the droplet-to vaporize, whileallowing a solid component to remain on the substrate; and a data inputunit for supplying droplet ejection information to the jet head, the jethead ejecting the droplet onto the substrate based on the dropletejection information so as to form the functional device in thefunctional device forming are.
 2. The apparatus according to claim 1,further comprising: a driving unit that moves at least one of the jethead and the holder relatively to the other so as to define a dropletejecting area of the jet head broader than the functional device formingarea of the substrate.
 3. The apparatus according to claim 1, whereinthe jet head has a droplet ejecting face for ejecting the dropletcontaining the functional material, and the droplet ejecting face facesthe functional device forming area of the substrate with a predetermineddistance between them.
 4. The apparatus according to claim 1, whereinthe holder adjusts and determines the position of the substrate, and thedriving unit operates so that the jet head and the holder moverelatively to each other in two orthogonal directions.
 5. The apparatusaccording to claim 1, wherein the jet head ejects the droplet using amechanical displacement force so that the droplet becomes sphericalimmediately before the droplet reaches the substrate.
 6. The apparatusaccording to claim 1, wherein the jet head-ejects the droplet using amechanical displacement force so that the droplet has an elongated shapealong the ejecting direction without a trailing droplet, and so that thelength of the elongated droplet does not exceed three times the diameterof the droplet.
 7. The apparatus according to claim 2, wherein thedriving unit includes a carriage on which the jet head is mounted, andthe carriage moves relatively to the substrate.
 8. The apparatusaccording to claim 1, wherein the holder is designed to be suitable forthe substrate having a thickness ranging from 2 mm to 15 mm, and theholder holds the substrate horizontally with the functional deviceforming area facing up.
 9. The apparatus according to claim 1, whereinthe holder holds the substrate horizontally, and the jet head ispositioned above the substrate at a distance of 0.1 mm to 10 mm from thesubstrate.
 10. The apparatus according to claim 1, further comprising: areservoir positioned under the substrate, the reservoir containing asolution of the functional material; and a flexible tube connecting thereservoir to the jet head.
 11. The apparatus according to claim 10,wherein the reservoir is an exchangeable cartridge.
 12. The apparatusaccording to claim 10, further comprising a pump positioned between thejet head and the reservoir.
 13. The apparatus according to claim 10,further comprising at least two types of filters positioned downstreamof the reservoir, wherein a most downstream filter is fixed so as not tobe detached.
 14. The apparatus according to claim 13, wherein the mostdownstream filter is provided in the jet head, and a filter mesh size ofthe most downstream filter is greater than that of an upstream filter.15. The apparatus according to claim 13, wherein the most downstreamfilter is provided in the jet head, and a filter trap capacity of themost downstream filter is smaller than that of an upstream filter. 16.The apparatus according to claim 3, further comprising maintenanceequipment positioned outside the holder and for capping the dropletejecting face of the jet head to evacuate the solution containing thefunctional material.
 17. The apparatus according to claim 16, whereinthe jet head is pivotable about a rotational axis so that the angle ofthe jet head with respect to a droplet ejecting direction is variable,and when the maintenance equipment is attached to the jet head, the jethead is turned away from the droplet ejecting direction.
 18. Theapparatus according to claim 16, further comprising: a reservoirpositioned under the substrate, the reservoir containing a solution ofthe functional material; a flexible tube connecting the reservoir to thejet head; and at least two types of filters positioned downstream of thereservoir, a most downstream filter being fixed so as not to bedetached, wherein the maintenance equipment suctions the solutioncontaining the functional material from the jet head so that the volumeof the suctioned solution is equal to or greater than the total internalvolume of the channel from the most downstream filter to nozzles. 19.The apparatus according to claim 1, wherein the jet head is comprised ofa set of multi-nozzle jet heads arranged apart from each other, and eachof the multi-nozzle jet heads has a row of nozzles and is capable ofejecting the droplet of a different type of solution of the functionalmaterial, and wherein the jet head is mounted on a carriage driven bythe driving unit, so that the row of the nozzles of each of themulti-nozzle jet heads is not parallel to a carriage moving direction.20. The apparatus according to claim 19, wherein each of themulti-nozzle jet heads ejects a different type of solution containing anorganic electroluminescent material that emits light of a differentcolor.
 21. The apparatus according to claim 1, wherein the dropletejection speed of the jet head is faster than the relative moving speedbetween the jet head and the substrate.
 22. The apparatus according toclaim 19, wherein the droplet ejection speed of each of the multi-nozzlejet heads is faster than the moving speed of the carriage.
 23. Theapparatus according to claim 1, wherein the droplet ejecting speed ofthe apparatus is 3 m/s to 10 m/s.
 24. The apparatus according to claim1, further comprising a clean air supply unit arranged around the jethead to supply clear air onto the substrate.
 25. A functional devicemounting board fabricating system comprising: a fabrication apparatusthat fabricates a functional device mounting board by ejecting a dropletof a solution containing a functional material from a jet head toward asubstrate held on a holder, while moving the jet head relatively to thesubstrate, based on droplet ejection information supplied to the jethead; and a clean air supply unit that supplies clean air to the dropletejection area on the substrate.
 26. The functional device mounting boardfabricating system according to claim 25, further comprising: a room inwhich the fabrication apparatus is placed, wherein the clean air supplyunit supplies the clean air into the room.
 27. The functional devicemounting board fabricating system according to claim 25, furthercomprising: a booth in which the fabrication apparatus is placed,wherein the clean air supply unit supplies the clean air into the booth.28. The system according to claim 25, wherein the droplet ejection speedof the fabrication apparatus is faster than the flowing speed of theclean air supplied from the clean air supply unit.
 29. A functionaldevice mounting board comprising: a substrate having a top face and arear face; a group of functional devices arranged in a matrix in afunctional device forming area defined on the top face, each of thefunctional devices being formed as a dot image formed by one or moredroplets of a solution containing a functional material; and aninformation pattern formed outside the functional device forming area onthe top face of the substrate.
 30. The functional device mounting boardaccording to claim 29, wherein the information pattern is formed as thedot image, and includes an identification pattern of the functionaldevice mounting board.
 31. The functional device mounting boardaccording to claim 29, wherein the information pattern is formed as thedot image, and includes a performance check pattern formed as said dotimage.
 32. A functional device mounting board comprising: a substratehaving a top face and a rear face; and a group of functional devicesarranged in a matrix in a functional device forming area defined on thetop face, each of the functional devices being formed as a dot imageformed by one or more droplets of a solution containing a functionalmaterial, wherein a roughness of the top face of the substrate is at orbelow 0.5 s.
 33. The functional device mounting board according to claim32, wherein each of the functional devices is formed of a different typeof said solution containing an organic electroluminescent material thatemits light of a different color.
 34. The functional device mountingboard according to claim 32, wherein the rear face has a roughnessgreater than that of the top face.
 35. The functional device mountingboard according to claim 32, wherein a roughness of the rear face of thesubstrate is at or above 1.0 s.
 36. The functional device mounting boardaccording to claim 32, wherein the rear face of the substrate has agroove.
 37. The functional device mounting board according to claim 32,wherein the rear face of the substrate has a ridge.
 38. The functionaldevice mounting board according to claim 32, wherein the substrate has achamfered corner.
 39. The functional device mounting board according toclaim 32, wherein the substrate has a corner having a shapedistinguishable from other corners.
 40. The functional device mountingboard according to claim 32, wherein the shape of the substrate isrectangular, and an indentation is formed along at least one of foursides of the substrate.
 41. The functional device mounting boardaccording to claim 32, wherein an edge of the substrate is chamfered.42. The functional device mounting board according to claim 41, whereinthe chamfered edge has a roughness greater than that of the top face ofthe substrate.
 43. The functional device mounting board according toclaim 32, wherein each of the functional devices is formed of one ormore dots made of said functional material and arranged in apredetermined direction, and wherein a distance between centers of twoadjacent dots is equal to or less than the diameter of the dot.
 44. Thefunctional device mounting board according to claim 32, wherein thesubstrate is made of a flexible material.
 45. The functional devicemounting board according to claim 44, wherein the functional devicemounting board is bent when functions of the functional devices areexhibited in actual use.
 46. An image display apparatus comprising: afunctional device mounting board having a group of functional devicesarranged in a functional device forming area on a first face of asubstrate, each of the functional devices being formed as a dot imageformed by one or more droplets of a solution containing a functionalmaterial; and a cover plate arranged so as to face the first face of thefunctional device mounting board.
 47. The image display apparatusaccording to claim 46, wherein the cover plate has a chamfered edge. 48.The image display apparatus according to claim 47, wherein the chamferededge of the cover plate has a roughness greater than that of thesubstrate of the functional device mounting board.
 49. The image displayapparatus according to claim 46, wherein the cover plate has a thicknessgreater than that of the functional device mounting board.
 50. The imagedisplay apparatus according to claim 46, wherein the cover plate is madeof a reinforced glass.
 51. An image display apparatus comprising: afunctional device mounting board having a group of functional devicesarranged in a functional device forming area on a first face of asubstrate, each of the functional devices being formed as a dot imageformed by one or more droplets of a solution containing a functionalmaterial; and a holder having a curved groove, wherein the functionaldevice mounting board is held in the curved groove of the holder so thatthe first face is bent with respect to a viewer.